The differences in placental pathology and neonatal outcome in singleton vs. twin gestation complicated by small for gestational age

Objective

We aimed to compare placental histopathology and neonatal outcome between dichorionic diamniotic (DCDA) twins and singleton pregnancies complicated by small for gestational age (SGA).

Methods

Medical files and placental pathology reports from all deliveries between 2008 and 2017 of SGA neonates, (birthweight?<?10th percentile), were reviewed. Comparison was made between singleton pregnancies complicated with SGA (singletons SGA group) and DCDA twin pregnancies (Twins SGA group), in which only one of the neonates was SGA. Placental diameters were compared between the groups. Placental lesions were classified into maternal and fetal vascular malperfusion lesions (MVM and FVM), maternal (MIR) and fetal (FIR) inflammatory responses, and chronic villitis. Neonatal outcome parameters included composite of early neonatal complications.

Results

The twins SGA group (n?=?66) was characterized by a higher maternal age (p?=?0.011), lower gestational age at delivery (34.9?±?3.1 vs. 37.7?±?2.6 weeks, p?<?0.001), and a higher rate of preeclampsia (p?=?0.010), compared to the singletons SGA group (n?=?500). Adverse composite neonatal outcome was more common in the twins SGA group (p?<?0.001). Placental villous lesions related to MVM (p?<?0.001) and composite MVM lesions (p?=?0.04) were more common in the singletons SGA group. On multivariate logistic regression analysis, the singletons SGA group was independently associated with placental villous lesions (aOR 3.6, 95% CI 1.9–7.0, p?<?0.001) and placental MVM lesions (aOR 2.44, 95% CI 1.29–4.61, p?=?0.006).

Conclusion

Placentas from SGA singleton pregnancies have more MVM lesions as compared to placentas from SGA twin pregnancies, suggesting different mechanisms involved in abnormal fetal growth in singleton and twin gestations.

     

Placental abnormalities associated with isolated single umbilical artery in small-for-gestational-age births

BackgroundPrevious studies have shown that pregnancies complicated by placentas with an isolated single umbilical artery (iSUA) are at increased risk for small-for-gestational-age (SGA) births. The etiology of SGA in this population, however, remains unknown.ObjectiveThe primary objective of this study was to evaluate whether placental abnormalities in pregnancies with SGA births differ according to the presence of iSUA.Study designThis was an observational study of all women with pathologic examination of the placenta after delivering a non-anomalous, singleton SGA neonate between January 2009 and August 2015. SGA was defined as birthweight less than 10th percentile for gestational age. Women were categorized according to whether they had an iSUA or a three-vessel cord. The following placental pathologies were compared between the groups using bivariable and multivariable analyses: SGA placenta, maternal vascular malperfusion, high grade fetal vascular malperfusion, and chronic villitis.Results1833 women were included in the analysis: 34 with iSUA and 1799 with three-vessel cord. More than 85% of women in both groups had at least one placental abnormality. After adjusting for nulliparity and neonatal gender, the presence of iSUA was associated with increased odds of high grade fetal vascular malperfusion (adjusted odds ratio 2.8, 95% confidence interval 1.1–7.5) and decreased odds of maternal vascular malperfusion (adjusted odds ratio 0.2, 95% confidence interval 0.1–0.9). There was no significant association with other pathologic findings.ConclusionPathologic placental findings associated with SGA birth differed based on umbilical cord composition. The presence of iSUA in an SGA birth was associated with a higher odds of high grade fetal vascular malperfusion abnormalities and lower odds of maternal vascular malperfusion abnormalities, compared to SGA birth with a 3VC.     

Placental maternal vascular malperfusion and adverse pregnancy outcomes in gestational diabetes mellitus

IntroductionMaternal vascular malperfusion (MVM) lesions represent hypoxic-ischemic damage to the placenta, and they are associated with adverse pregnancy outcomes. Women with gestational diabetes (GDM) are at increased risk for pregnancy complications, so we set out to characterize the prevalence and clinical correlates of MVM lesions in this cohort.MethodsThis was a retrospective cohort study of 1187/1374 (86.4%) women with GDM delivered between 2009 and 2012 who had placental pathology available. Placental lesions of all types were tabulated and grouped into constructs of related entities. MVM lesions specifically included villous infarcts, decidual vasculopathy, increased syncytial knots, perivillous fibrin, and fibrin deposition. We compared maternal characteristics between women with and without MVM lesions, and we also assessed the impact of these lesions on birth weight, preterm birth, and pre-eclampsia using multivariable logistic regression analysis.ResultsMVM lesions were the most common placental lesion type in women with GDM (n = 362, 30.5%). Excess gestational weight gain was independently associated with MVM lesions (aOR 1.42, 95% CI 1.06–1.91, p = 0.02) after adjusting for maternal characteristics. MVM lesions were associated with lower birth weight (−90.3 g, 95% CI -148.0 to −32.7, p = 0.002), as well as a 2-fold increased risk for delivery of a small for gestational age infant (10.8 vs 5.9%, p = 0.01) in overweight and obese women. MVM lesions were also associated with increased risk for preterm birth <34 weeks (adjusted OR 2.36, 95% CI 1.31–4.23, p = 0.004) and hypertensive disorders of pregnancy (HDP; adjusted OR 1.58, 95% CI 1.13–2.22, p = 0.02).DiscussionPlacental maternal vascular malperfusion lesions may be one pathway linking excess gestational weight gain to adverse pregnancy outcomes in women with GDM, and future studies are needed to identify metabolic factors that may explain this association.     

The association between placental histopathology and autism spectrum disorder

IntroductionResearch suggests that autism spectrum disorder (ASD) has its origins in utero. This study examines the association between evidence of placental histopathology and ASD.MethodsAdministrative claims data and medical records data were used to identify ASD cases (N = 55) and matched controls (N = 199) born at New York Methodist Hospital between 2007 and 2014 and subsequently seen in affiliated pediatrics clinics. Placentas from all births during this time period were reviewed as part of routine care. Data were analyzed using conditional logistic regression to account for the matched (gender, gestational age, and birth weight) design.ResultsAcute placental inflammation, regardless of type was associated with an increased risk of ASD (odds ratio [OR] = 3.14, 95% CI = 1.39, 6.95). Chronic uteroplacental vasculitis (OR = 7.13; 95% CI = 1.17, 43.38), the fetal inflammatory response in the chorionic plate vessels (OR = 5.12; 95% CI = 2.02, 12.96), and maternal vascular malperfusion pathology (OR = 12.29; 95% CI = 1.37, 110.69) were associated with an increased risk of ASD. Placental villous edema was associated with a decreased risk of ASD (OR = 0.05; 95% CI = 0.0005, 0.42). In subanalyses among male placentas acute inflammation overall, fetal inflammatory response in the chorionic plate vessels, and maternal vascular malperfusion pathology remained significantly associated with an increased risk of ASD whereas placental villous edema remained associated with a decreased risk of ASD.DiscussionHistologic evidence of placental inflammation and maternal vascular malperfusion pathology are associated with ASD.     

Villitis of unknown etiology – prevalence and clinical associations

Objectives: We aimed to determine the association of villitis of unknown etiology (VUE) in complicated and uncomplicated pregnancies.

Methods: Placentas from term pregnancies (≥37 weeks) were sent to histopathology evaluation. Maternal and labor characteristics and pathological reports were compared between placentas with VUE (VUE group) and without VUE (controls). Immunohistochemical studies were performed to identify T-cells infiltration in foci of VUE. Placentas were analyzed for concomitant lesions consistent with maternal malperfusion, fetal vascular supply and inflammatory lesions. Small for gestational age (SGA) was defined as birth weight below the 10th %.

Results: A total of 1203 placentas were obtained, in which VUE was diagnosed in 5% (n?=?60). Compared to controls ((n?=?1143), the VUE group was characterized by lower birth weights, p?<?0.001, higher rate of SGA, p?=?0.009 and lower placental weight, p?<?0.001. By logistic regression analysis, after controlling for gestational age, nulliparity, pregnancy complications, obesity, smoking and SGA, only SGA was found to be independently associated with VUE, aOR: 2.3, 95% CI: 1.2–4.4, p?=?0.012. Additionally, VUA and maternal malperfusion lesions were found to be independent risk factors for the development SGA.

Conclusions: VUE is associated with lower birth weights, SGA and lower placental weight. Both VUE and maternal malperfusion lesions are risk factors for the development of SGA.     

The Northwestern twin chorionicity study: testing the 'placental crowding' hypothesis

OBJECTIVE: To evaluate the relation between placental proximity and frequency of birth weight discordance and small-for-gestational age (SGA) infants. STUDY DESIGN: Retrospective three-tier chorionicity analysis of 1155 twin placentas comparing birth weight characteristics of the twins in different placental types. RESULTS: Dichorionic-separate, but not dichorionic-fused twins, are heavier than monochorionic-diamniotic and monoamniotic twins (2376+/-721 vs. 2274+/-770, P < 0.006, and 2376+/-721 vs. 2166+/-782, P < 0.04). SGA twins are less frequent among dichorionic twins (OR 0.4; 95% CI 0.3, 0.6). Fewer sets with two SGA infants are present among dichorionic-separate compared to monochorionic-diamniotic pairs (OR 0.3; 95% CI 0.1, 0.8). The same trends are found when comparing all dichorionic to all monochorionic twins. Twins of all placental types have similar gestational ages and discordance values. CONCLUSIONS: Dichorionic-separate placentas are least likely to experience 'placental crowding' and thus are associated with heavier twins and fewer sets with one or two SGA infants.     

Second Trimester Placental Growth Factor Levels and Placental Histopathology in Low-Risk Nulliparous Pregnancies

ObjectivePlacental growth factor (PlGF) levels are lower at delivery in pregnancies with preeclampsia or fetuses small for gestational age (SGA). These obstetrical complications are typically mediated by placental dysfunction, most commonly related to the specific placental phenotype termed placental maternal vascular malperfusion (MVM). The objective of this study was to determine the relationship between PlGF levels in the second trimester and the development of placental diseases that underlie adverse perinatal outcomes.MethodsWe performed a secondary analysis of the prospective Placental Health Study in unselected healthy nulliparous women (n = 773). Maternal demographic data, Doppler ultrasound measurements, and plasma PlGF levels at 15 to 18 weeks gestation were analyzed for association with pregnancy outcomes and placental pathology following delivery.ResultsLow PlGF levels in the second trimester (<10th percentile; <72 pg/mL) was associated with preterm delivery (<37 weeks; 26% vs. 6%, P < 0.001; unadjusted odds ratio (OR) 5.75, 95% CI 3.2–10.5), reduced mean birth weight (2998 vs. 3320 g, P < 0.001), SGA deliveries (25% vs. 11%, P = 0.001; OR 2.6, 95% CI 1.5–4.6), and preeclampsia (7% vs. 2%, P = 0.02; OR 4.3, 95% CI 1.5-12.8) relative to normal PlGF levels (≥10th percentile; ≥72 pg/mL). Low PlGF was associated with lower mean placental weight (447 vs. 471 g, P = 0.01), aberrant cord insertion (25% vs. 12%, P = 0.001) and a pathologic diagnosis of MVM (18% vs. 11%, P = 0.04; OR 1.9, 95% CI 1.01–3.55) but not with other placental pathologies.ConclusionMVM placental pathology and related adverse perinatal outcomes are associated with low PlGF in the early second trimester for healthy nulliparous women.     

Pregnancy outcome and placental pathology in small for gestational age neonates in relation to the severity of their growth restriction

Purpose: To investigate neonatal outcome and placental pathology in pregnancies complicated with small for gestational age neonates (SGA), in relation to the severity of growth restriction.

Methods: The medical records and placental histology reports of all neonates with a birth-weight (BW) ≤10th percentile, born between 24–42 weeks, during 2010–2015, were reviewed. Placental lesions were classified into maternal and fetal vascular malperfusion (MVM and FVM) lesions. Results were compared between neonates with BW <5th percentile (severe SGA group), neonates with BW between 5th–10th percentile (mild SGA group) and a control group of appropriate for gestational age (AGA) neonates. Composite neonatal outcome was defined as one or more of early complications.

Results: Overall, 753 neonates were included, 238 in the severe SGA group, 266 in the mild SGA group, and 249 in the control group. The severe SGA group had higher rates of composite adverse neonatal outcome as compared with the mild SGA and control groups (37.2 versus 17.6%, versus 24.5%, respectively, p?p?Conclusions: Worse neonatal outcome and more placental MVM and FVM lesions correlate with the severity of neonatal growth restriction in a “dose-dependent” manner.     

Placental growth factor as a marker of fetal growth restriction caused by placental dysfunction

IntroductionDiscriminating between placentally-mediated fetal growth restriction and constitutionally-small fetuses is a challenge in obstetric practice. Placental growth factor (PlGF), measurable in the maternal circulation, may have this discriminatory capacity.MethodsPlasma PlGF was measured in women presenting with suspected fetal growth restriction (FGR; ultrasound fetal abdominal circumference <10th percentile for gestational age) at sites in Canada, New Zealand and the United Kingdom. When available, placenta tissue underwent histopathological examination for lesions indicating placental dysfunction, blinded to PlGF and clinical outcome. Lesions were evaluated according to pre-specified severity criteria and an overall severity grade was assigned (0–3, absent to severe). Low PlGF (concentration <5th percentile for gestational age) to identify placental FGR (severity grade ≥ 2) was assessed and compared with routine parameters for fetal assessment. For all cases, the relationship between PlGF and the sampling-to-delivery interval was determined.ResultsLow PlGF identified placental FGR with an area under the receiver-operator characteristic curve of 0.96 [95% CI 0.93–0.98], 98.2% [95% CI 90.5–99.9] sensitivity and 75.1% [95% CI 67.6–81.7] specificity. Negative and positive predictive values were 99.2% [95% CI 95.4–99.9] and 58.5% [95% CI 47.9–68.6], respectively. Low PlGF outperformed gestational age, abdominal circumference and umbilical artery resistance index in predicting placental FGR. Very low PlGF (<12 pg/mL) was associated with shorter sampling-to-delivery intervals than normal PlGF (13 vs. 29.5 days, P < 0.0001).DiscussionLow PlGF identifies small fetuses with significant underlying placental pathology and is a promising tool for antenatal discrimination of FGR from fetuses who are constitutionally-small.     

Birthweight of IVF children is still a current issue and still related to maternal factors

Research questionDoes fresh embryo transfer after IVF with or without intracytoplasmic sperm injection (ICSI) increase the small for gestational age (SGA) rate, and frozen embryo transfer (FET) after IVF with or without ICSI increase the large for gestational age (LGA) rate versus natural conception?DesignRetrospective comparison of an exposed historical group/cohort involving singletons conceived after fresh embryo transfer and after FET with an unexposed group/cohort involving singletons conceived after a natural conception.ResultsA total of 1961 fresh embryo transfer babies and 366 FET babies were compared with 6981 natural conception babies. The SGA rate in fresh embryo transfer babies was not significantly different to natural conception babies (6.9% versus 6.8%, P = 0.856). This outcome was not influenced by the fresh embryo transfer (adjusted odds ratio [aOR] 1.0; 95% confidence interval [CI] 0.8–1.3), but rather by a low rate of multiparity (aOR 0.5; 95% CI 0.3–0.7), advanced maternal age (aOR 1.1; 95% CI 1.0–1.2), maternal underweight (aOR 1.5; 95% CI 1.1–2.1), maternal smoking or cessation during pregnancy (aOR 1.8; 95% CI 1.4–2.3), pre-existing hypertension (aOR 2.3; 95% CI 1.3–4.1) and pregnancy-induced hypertension (aOR 2.5; 95% CI 1.7–3.7). The LGA rate in FET babies was significantly different from natural conception babies (6.6% versus 3.2%, P = 0.012). This outcome was influenced by the transfer of frozen embryos (aOR 2.2; 95% CI 1.3–3.8) and by a high maternal weight (aOR 1.9; 95% CI 1.1–3.6).ConclusionsMaternal background and obstetric parameters are more likely to influence the SGA rate than fresh embryo transfer conception. FET conception could be associated with an increase in LGA rate.     

First-trimester placental thickness and the risk of preeclampsia or SGA

IntroductionPlacental thickness in the second trimester of pregnancy has been associated with risks of placenta-mediated complications of pregnancy. We aimed to estimate the association between first-trimester maximum placental thickness and the subsequent risk of preeclampsia and/or the delivery of small-for-gestational-age (SGA) neonate.MethodsProspective cohort study of women recruited at 11–14 weeks gestation. Placental thickness was measured at its apparent center and reported in multiple of median (MoM) adjusted for gestational age. Participants were followed until delivery for pregnancy outcomes. Placental measurements of participants who developed preeclampsia and/or delivered SGA neonate (defined as birth weight below 10th percentile) were compared with those who did not using non-parametric statistical analyses.ResultsWe recruited 991 participants at a mean gestational age of 12.7 ± 0.7 weeks of gestation. SGA (n = 52) was associated with reduced 1st trimester placental thickness (median: 0.89 MoM; interquartile (IQ): 0.75–1.02 vs 0.98 MoM; IQ: 0.84–1.15; p < 0.01). Pregnancies that developed preeclampsia (n = 20) tended to have greater placental thickness (median: 1.10 MoM; IQ: 0.93–1.25 vs 0.97 MoM; IQ: 0.84–1.14; p = 0.06) with values > 1.2 MoM significantly increasing the risk for preeclampsia (relative risk: 3.6; 95%CI: 1.5–8.6, p < 0.01). Pregnancies complicated by both SGA and preeclampsia (n = 5) had similar placental thickness in the first-trimester in comparison with uncomplicated pregnancies (median: 1.03 MoM; IQ: 0.89–1.42 vs 0.98 MoM; IQ: 0.84–1.14; p = 0.33).ConclusionFirst-trimester placental thickness diverges in pregnancies at risk of preeclampsia (increased) or SGA (decreased), but remains within normal values in pregnancies at risk of both conditions, suggesting that the underlying pathologies have some opposing effects on early placental growth. The current findings should be validated in a larger cohort.     

Neighbourhood Income and Risk of Having an Infant With Concomitant Preterm Birth and Severe Small for Gestational Age Birth Weight

ObjectiveSocioeconomic position gradients have been individually demonstrated for preterm birth (PTB) at <37 weeks gestation and severe small for gestational age birth weight at <5th percentile (SGA). It is not known how neighbourhood income is related to the combination of PTB and severe SGA, a state reflective of greater placental dysfunction and higher risk of neonatal morbidity and mortality than PTB or severe SGA alone.MethodsThis population-based study comprised all 1 367 656 singleton live births in Ontario from 2002 to 2011. Multinomial logistic regression was used to estimate the odds of PTB with severe SGA, PTB without severe SGA, and severe SGA without PTB, compared with neither PTB nor severe SGA, in relation to neighbourhood income quintile (Q). The highest income quintile, Q5, served as the exposure referent. Adjusted odds ratios (aORs) were adjusted for maternal age at delivery, parity, marital status, and world region of birth (Canadian Task Force Classification II-2).ResultsRelative to women residing in Q5 (2.3 per 1000), the rate of PTB with severe SGA was highest among those in Q1 (3.6 per 1000), with an aOR of 1.34 (95% confidence interval [CI] 1.20–1.50). The corresponding aORs were 1.23 (95% CI 1.09–1.37) for Q2, 1.14 (95% CI 1.02–1.28) for Q3, and 1.06 (95% CI 0.95–1.20) for Q4. Less pronounced aORs were seen for each individual outcome of PTB and severe SGA.ConclusionWomen residing in the lowest-income areas are at highest risk of having a fetus born too small and too soon. Future research should focus on identifying those women most predisposed to combined PTB and severe SGA.     

Placental soluble fms-like tyrosine kinase expression in small for gestational age infants and risk for adverse outcomes

IntroductionSoluble fms-like tyrosine kinase 1 (sFLT-1) is an anti-angiogenic factor implicated in the pathogenesis of preterm preeclampsia. We evaluated sFLT-1 expression and placental pathology in pregnancies complicated by small for gestational age (SGA) infants (<10th percentile), without evidence of preeclampsia.MethodsClinical and histologic data were compared between groups with high or low sFLT-1 expression determined by immunohistochemistry on archived placentas.ResultsNineteen of 69 placentas showed high sFLT-1 expression. The high sFLT-1 group had higher predelivery median systolic blood pressure (BP); 140 (interquartile range (IQR) 133–152) vs. 126 (118–139) mm Hg (p = 0.003), and median diastolic BP; 87 (78–94) vs. 77.5 (71–86) mm Hg (p = 0.02). Abnormal umbilical Doppler abnormalities were more prevalent; 89.5% vs. 46% (p = 0.001). These pregnancies delivered earlier; 31.9 weeks (28.3–34.7 weeks) vs. 37.1 weeks (33.7–38.7 weeks) (p < 0.001), and infants had lower birthweight; 980 grams (520–1545 grams) vs. 2087.5 grams (1455–2340 grams) (p < 0.001). Placental-weight to fetal-weight ratios, a marker of vascular insufficiency, was increased in the high sFlt-1 group: 0.18 (0.14–0.28) vs 0.15 (0.13–0.18), p = 0.03. Placentas with high sFLT-1 showed more decidual vasculopathy; 42.1% vs. 10.0% (p = 0.005), infarction; 36.8% vs. 14.0% (p = 0.048), distal villous hypoplasia; 78.9% vs. 36.0% (p = 0.001), and fetal thrombotic vasculopathy; 47.4% vs. 16.0% (p = 0.01).DiscussionPlacental sFLT-1 expression is upregulated in approximately 28% of non-preeclamptic pregnancies complicated by SGA infants. These pregnancies showed increased placental vascular pathology, more umbilical Doppler abnormalities, and earlier delivery with lower birthweight. A subgroup of non-preeclamptic fetal growth restriction with upregulated sFlt-1 expression may share a common pathogenic pathway with preterm preeclampsia. This subgroup is worthy of additional study.     

Hypertension in dichorionic twin gestations: how is birthweight affected?*

Objective: To examine the association between hypertension (HTN) and discordant or small for gestational age (SGA) birthweights among dichorionic twin pregnancies.

Methods: Retrospective cohort of dichorionic twin pregnancies delivered at ≥24 0/7 weeks from 2002 to 2015. Women with HTN in pregnancy (gestational HTN or preeclampsia) and chronic HTN (cHTN) were compared to those with uncomplicated dichorionic pregnancies. Outcomes were any discordance (≥20% difference within each twin pair), discordance with at least one twin also SGA (≥20% discordance with at least one twin also SGA?<10th percentile), and SGA alone of one or both twins (<5th and?<10th percentile).

Results: 474 Dichorionic pregnancies were identified. Women with HTN in pregnancy had an adjusted odds ratio (aOR) of 2.68 (95% CI 1.48-4.87) for any discordance and 2.94 (1.57-5.48) for discordance with at least one twin also SGA. These aORs for women with cHTN were 4.65 (1.39-15.52) and 4.37 (1.21-15.76), respectively. Significant differences were not observed for SGA alone of one or both twins.

Conclusion: Among dichorionic pregnancies, both women with HTN in pregnancy and cHTN demonstrated increased odds of any discordant growth, as well as discordance with concurrent SGA of at least one twin. Odds of these outcomes were greatest with cHTN.     

Differences in fetal growth, discordancy, and placental pathology in reduced versus nonreduced twins

This study evaluated the effect of multifetal pregnancy reduction on the incidence of small for gestational age (SGA) and discordance in reduced versus nonreduced twins and differences in placental pathology. A computerized ultrasound database was used to identify diamniotic-dichorionic twins who delivered at our institution. Reduced (n = 36) versus nonreduced twins (n = 243) were compared for differences in rates of SGA and discordancy (>or= 20%.) The groups were compared for differences in maternal and neonatal characteristics, as well as differences in placental pathology. Chi-square tests were used to compare differences in means. Stepwise logistic regression was used to adjust for potential confounders including placental pathology. The rate of SGA in either twin A or B remained nonsignificant after adjustment for the use of assisted reproductive technology and gestational age at delivery in the stepwise logistic model (odds ratio, 1.7 95%; confidence interval, 0.5, 5.2). The average discordance at delivery was 12.4% in reduced versus 11.4% in the nonreduced twins ( P = 0.54). We found no overall differences in placental pathology between the two groups. Reduced and nonreduced twins have no significant differences in SGA fetuses, growth discordancy, or placental pathology.     

Small for gestational age newborns – does pre-recognition make a difference in pregnancy outcome?

Objective: We aimed to evaluate whether pre-recognition of small for gestational age (SGA) at late preterm or term pregnancies, has an impact on pregnancy outcome.

Methods: Retrospective analysis of SGA newborns, stratified to those with suspected or unsuspected IUGR according the sonographic estimated fetal weight (EFW), below the 10th percentile for gestational age (n?=?619), with fetuses not suspected as SGA (EFW ≥10th percentile) preformed up to 7 days prior to delivery (n?=?1770).

Results: SGA was correctly diagnosed prior to delivery in 26% of the fetuses. Women with suspected SGA were delivered earlier (37.9?±?1.7 versus 38.8?±?1.4 weeks, p?<?0.001) and at a lower birth weight (2280?±?321 versus 2454?±?263 grams, p?<?0.001). They also had higher rates of induction of labor (19.1% versus 6.2%, p?<?0.001) and cesarean delivery (29.1% versus 19.8%, p?<?0.001). Fetuses suspected for SGA had higher rate of neonatal adverse outcome, but on multivariate analysis suspected SGA (aOR 0.41, 95% CI 0.20–0.86), birthweight (aOR 0.67, 95% CI 0.5 to ?0.77 for each additional 50?g), gestational age at delivery (aOR 0.63, 95% CI 0.56–0.71 for each additional week) and spontaneous vaginal delivery (aOR 0.88, 95% CI 0.19–3.89) were independently associated with an improved neonatal composite outcome.

Conclusion: Identification of SGA may improve neonatal outcome. However, by itself, it is not an indication for intervention, which may lead to adverse outcome.     

Pregnancy outcome after multifetal pregnancy reduction of triplets to twins versus reduction to singletons

Research questionDoes fetal reduction of triplet pregnancies to singleton result in superior obstetric and neonatal outcomes compared with triplets reduced to twins?DesignA historical cohort study including 285 trichorionic and dichorionic triplet pregnancies that underwent abdominal fetal reduction at 11–14 weeks in a single tertiary referral centre. The study population comprised two groups: reduction to twins (n = 223) and singletons (n = 62). Main outcome measures were rates of pregnancy complications, preterm delivery and neonatal outcomes. Non-parametric statistical methods were employed.ResultsTriplet pregnancies reduced to twins delivered earlier (36 versus 39 weeks, P < 0.001) with higher prevalence of Caesarean section (71.1% versus 32.2%, P < 0.001) compared with triplets reduced to singletons. Preterm delivery rates were significantly higher in twins compared with singletons prior to 37 weeks (56.9% versus 13.6%, P < 0.001), 34 weeks (20.2% versus 3.4%, P = 0.002) and 32 weeks (9.6% versus 0%, P = 0.01). No significant difference was found in the rate of pregnancy loss before 24 weeks (1.3% in twins versus 4.8% in singletons, P = 0.12) or in the rate of intrauterine fetal death after 24 weeks (0.4% versus 0%, P = 1.0). Both groups had comparable obstetrical complications and neonatal outcomes, except for higher rates of neonatal intensive care unit admission in twins (31.9% versus 6.8%, P < 0.001).ConclusionsReduction of triplets to singletons rather than twins resulted in superior obstetric outcomes without increasing the procedure-related complications. However, because the rate of extreme prematurity in pregnancies reduced to twins was low, the overall outcome of those pregnancies was favourable. Therefore, the option of reduction to singletons should be considered in cases where the risk of prematurity seems exceptionally high.     

New-onset hypertension in late pregnancy and fetal growth: different associations between singletons and twins.

OBJECTIVE: To compare the effects of new-onset hypertension (NOH) in late pregnancy on fetal growth in singletons and twins. METHODS: A retrospective cohort study was conducted to evaluate the effect of NOH on fetal growth in 17, 720, 900 singletons and 463, 104 twins born in the United States between 1995 and 2000. RESULTS: NOH was associated with lower mean birth weight in both preterm and term singletons. Increased risk of low birth weight and decreased risk of high birth weight was associated with NOH in preterm and term singletons. NOH was associated with increased risk for small-for-gestational-age (SGA) births and decreased risk for large-for-gestational-age (LGA) births in preterm singletons, whereas it was associated with increased risk of both SGA and LGA births in term singletons. NOH was associated with higher mean birth weight in early preterm twins, and lower mean birth weight in term twins. Decreased risk for low birth weight was found in the NOH group among early preterm twins, and increased risk for low birth weight in term twins. NOH was associated with increased risk of SGA births and decreased risk for large-for-gestational-age (LGA) births in early preterm twins, while increased risk of SGA births in term twins. CONCLUSION: NOH is associated with slower fetal growth in singletons delivered at different gestational ages, but the effect varies in twins depending on gestational age at delivery with faster growth in early preterm twins.     

The impact of chorionicity on umbilical cord acid–base values in twin gestations

Objective: To evaluate the impact of chorionicity on inter-twin differences in acid–base status at birth.

Methods: Records for twin pregnancies delivered at ??24 weeks' gestation from 1 January 1990 to 31 June 2000 were reviewed. Collected data included maternal demographics, gestational age, fetal presentation, anesthesia, delivery mode, inter-twin interval, umbilical artery (UA) and venous (UV) acid–base values, Apgar scores and birth weights. The influence of chorionicity on umbilical cord biochemistry was evaluated. (p?<?0.05 was considered significant.)

Results: Analysis was carried out in 87 twin pairs (29 monochorionic, MC; and 58 dichorionic, DC). MC and DC twins were similar in maternal age (25.5 vs. 28.2 years), estimated gestational age (33.7 vs. 33.6 weeks), Cesarean delivery (55.2 vs. 52.6%), delivery interval (10 v s.5?min) and respective birth weights (twin A,1882 vs. 1981; and twin B,1828 vs. 1872?g). MC first twins had a higher UA pH (7.31?±?0.05 vs. 7.26?±?0.08; p?=?0.0005) than DC first twins. MC first and second twins had higher UA and UV bicarbonate levels than their DC counterparts (ΔpH?=?21.7?±?5.1 vs. 18.5?±?3.1?mmol/l and 22.0?±?3.5 vs. 19.6?±?2.5?mmol/l, respectively; p?=?0.003). MC twins were more discordant in UA pH than DC twins (ΔpH?=?0.043?±?0.09 vs. 0.003?±?0.07; p?=?0.009). MC and DC twins had a similar venous pH (ΔpH?=?0.01?±?0.06 vs. 0.02?±?0.06; p?=?0.5).

Conclusions: There is a significant association between placental chorionicity and umbilical cord biochemistry in twins. Although it is possible that the mechanism of this finding is related to placental angioarchitecture, it is unlikely to be a result of simple mixing of blood volumes between twins. The physiology of underlying processes requires further study.     

Perinatal outcomes with intrahepatic cholestasis of pregnancy in twin pregnancies

Objective: To describe perinatal outcomes of twin pregnancies complicated by intrahepatic cholestasis of pregnancy (ICP).

Methods: We conducted a retrospective cohort study of women delivered at a large tertiary obstetric center in Shanghai, China from January 2006 to May 2014. Delivery data were abstracted from medical records of all twin gestations delivered at the hospital.

Results: A total of 129/1922(6.7%) twin and 1190/92?273 singleton (1.3%) pregnancies were complicated by ICP. An increased risk of stillbirth among twin pregnancies was observed (3.9% and 0.8% in the ICP and non-ICP groups, respectively; aOR 5.75, 95% CI 2.00–16.6). Stillbirths with ICP and twins occurred between 33 and 35 weeks gestation compared to 36–38 weeks gestation among singletons. ICP in twins was also associated with an increased risk of preterm birth (<37 weeks) with an aOR of 4.17 (95% CI 2.47–7.04) and an aOR of 1.89 (95% CI 1.26–2.85) for delivery <35 weeks. Twin pregnancies complicated by ICP also had increased meconium staining of amniotic fluid and lower birth weight.

Conclusions: Twin pregnancies with ICP have significantly increased risks of adverse perinatal outcomes including stillbirth and preterm birth. Stillbirth occurs at an earlier gestational age in twin gestation compared to singletons, suggesting that earlier scheduled delivery should be considered in these women.