Milk consumption during pregnancy and infant birthweight

AIM: To examine the risk of low birthweight (<2500 g, LBW), intrauterine growth retardation (IUGR) and preterm birth (gestational age <37 wk) in relation to milk intake. METHODS: Observational study in southeast Sweden. Questionnaires were used to collect data on milk consumption during pregnancy and infant birthweight from mother-infant pairs during a 2-y period as part of the ABIS (All Babies in Southeast Sweden) study. Data on IUGR were obtained through the Swedish medical birth registry. RESULTS: Adjusting for confounders, low milk intake during pregnancy was associated with an increased risk of IUGR (p = 0.019; n = 12880). LBW (p = 0.191) and preterm birth (p = 0.921) were not associated with milk intake during pregnancy. CONCLUSION: This study indicates that low milk intake in the pregnant mother may be associated with IUGR of the newborn. We cannot exclude the possibility that the correlation found between milk consumption and intrauterine growth may be due to undetected confounders. Hence, further research is needed to evaluate the relationship between low milk intake, birthweight and risk of IUGR.     

Relationship of tibial speed of sound and lower limb length to nutrient intake in preterm infants

BACKGROUND: Metabolic bone disease of prematurity is characterised by impaired postnatal mineralisation of the rapidly growing infant skeleton. OBJECTIVE: To longitudinally evaluate postnatal changes in tibial speed of sound (tSOS; which reflects cortical thickness and bone mineral density) and lower limb length (LLL; a measure of tibial growth) in very low birthweight preterm infants receiving contemporary neonatal care. METHODS: tSOS and LLL were measured using a quantitative ultrasound device and an electronic neonatal knemometer, respectively, in the same limb, weekly, for a median period of four weeks (3-16 weeks) in 84 preterm infants (median gestation 26.8 weeks (range 23-35.2 weeks) and median birth weight 869.5 g (range 418-1481 g)). RESULTS: Initial tSOS and LLL were correlated with gestation (r = 0.42, p<0.001; r = 0.76, p<0.001, respectively) and birth weight (r = 0.23, p = 0.038; r = 0.93, p<0.001, respectively). Postnatally, tSOS decreased (r = -0.15, p = 0.011) whereas LLL increased (r = 0.96, p<0.001) with age. The rate of postnatal change in LLL, but not in tSOS, was positively influenced by intake of calcium (p = 0.03), phosphorus (p = 0.01) and vitamin D (p = 0.03). CONCLUSIONS: The postnatal decline in tSOS, which is probably due to cortical thinning secondary to endocortical bone loss, and increase in LLL provide new insight into the development of long bones in preterm infants.     

Short-term outcome in infants with a birthweight less than 501 grams

AIM: To report survival and morbidity until discharge in preterm infants <501 g with life support started immediately after birth. Methods/study design: Cohort study of all preterm infants with birthweights < 501 g born in three tertiary perinatal centres between 1 January 1998 and 31 December 2001 (gestational age (GA) 25.2 [21.0-30.7] wk; birthweight 435 [290-500] g; median [range]). RESULTS: A total of 107 infants with birthweights <501 g were born. Twenty-nine were stillborn. A prenatal decision to initiate life support immediately after birth was reached in 9/37 (24%) infants <24.0 wk GA and in 39/42 (93%) infants > or =24.0 wk GA. Survival was 3/37 (8%) and 26/41 (63%) in infants <24 wk GA and > or =24.0 wk GA, respectively. Twenty-nine of the 48 infants with immediate life support (60%) survived (95% CI: 46-75%). Forty-two of these 48 (88%) infants were small for gestational age. No infant without immediate life support survived (0/30). Twenty-three (79%) survivors developed chronic lung disease (CLD) and eight (28%) received photocoagulation for retinopathy of prematurity (ROP). CONCLUSION: In this population of extremely low birthweight infants, survival was higher than in previous studies when life support was provided immediately after birth. Short-term morbidity was similar to other studies. The presented data on survival support our concept to offer immediate life support after birth in preterm infants with birthweights <501 g. The long-term outcome of these infants needs to be assessed urgently.     

Nurse staffing in relation to risk-adjusted mortality in neonatal care

OBJECTIVE: To assess whether risk-adjusted mortality in very low birthweight or preterm infants is associated with levels of nursing provision. DESIGN: Prospective study of risk-adjusted mortality in infants admitted to a random sample of neonatal units. SETTING: Fifty four UK neonatal intensive care units stratified by: patient volume; consultant availability; nurse:cot ratios. PATIENTS: A group of 2585 very low birthweight (birthweight <1500 g) or preterm (<31 weeks gestation) infants. MAIN OUTCOME MEASURE: Death before discharge or planned deaths at home, excluding lethal malformations, after adjusting for initial risk 12 hours after birth using gestation at birth and measures of illness severity in relation to nursing provision calculated for each baby's neonatal unit stay. RESULTS: A total of 57% of nursing shifts were understaffed, with greater shortages at weekends. Risk-adjusted mortality was inversely related to the provision of nurses with specialist neonatal qualifications (OR 0.67; 95% CI 0.42 to 0.97). Increasing the ratio of nurses with neonatal qualifications to intensive care and high dependency infants to 1:1 was associated with a decrease in risk-adjusted mortality of 48% (OR: 0.52, 95% CI: 0.33, 0.83). CONCLUSIONS: Risk-adjusted mortality did not differ across neonatal units. However, survival in neonatal care for very low birthweight or preterm infants was related to proportion of nurses with neonatal qualifications per shift. The findings could be used to support specific standards of specialist nursing provision in neonatal and other areas of intensive and high dependency care.     

Pregnancy loss and role of infant HIV status on perinatal mortality among HIV-infected women

ABSTRACT: BACKGROUND: HIV-infected women, particularly those with advanced disease, may have higher rates of pregnancy loss (miscarriage and stillbirth) and neonatal mortality than uninfected women. Here we examine risk factors for these adverse pregnancy outcomes in a cohort of HIVinfected women in Zambia considering the impact of infant HIV status. METHODS: A total of 1229 HIV-infected pregnant women were enrolled (2001-2004) in Lusaka, Zambia and followed to pregnancy outcome. Live-born infants were tested for HIV by PCR at birth, 1 week and 5 weeks. Obstetric and neonatal data were collected after delivery and the rates of neonatal (<28 days) and early mortality (<70 days) were described using Kaplan-Meier methods. RESULTS: The ratio of miscarriage and stillbirth per 100 live-births were 3.1 and 2.6, respectively. Higher maternal plasma viral load (adjusted odds ratio [AOR] for each log10 increase in HIV RNA copies/ml = 1.90; 95% confidence interval [CI] 1.10-3.27) and being symptomatic were associated with an increased risk of stillbirth (AOR = 3.19; 95% CI 1.46-6.97), and decreasing maternal CD4 count by 100 cells/mm3 with an increased risk of miscarriage (OR = 1.25; 95% CI 1.02-1.54). The neonatal mortality rate was 4.3 per 100 increasing to 6.3 by 70 days. Intrauterine HIV infection was not associated with neonatal morality but became associated with mortality through 70 days (adjusted hazard ratio = 2.76; 95% CI 1.25-6.08). Low birth weight and cessation of breastfeeding were significant risk factors for both neonatal and early mortality independent of infant HIV infection. CONCLUSIONS: More advanced maternal HIV disease was associated with adverse pregnancy outcomes. Excess neonatal mortality in HIV-infected women was not primarily explained by infant HIV infection but was strongly associated with low birth weight and prematurity. Intrauterine HIV infection contributed to mortality as early as 70 days of infant age. Interventions to improve pregnancy outcomes for HIV-infected women are needed to complement necessary therapeutic and prophylactic antiretroviral interventions.     

Chronic lung disease in very low birthweight infants: A prospective population-based study

A prospective population-based study of chronic lung disease among all very low birthweight infants (birthweight 500-1499 g) born in New Zealand in 1986 is reported. Of 413 of these infants admitted to neonatal units, 355 (86%) survived to 28 days. An additional 50 infants were recorded as liveborn but died in the labour ward or other place of birth. Both observed survival and survival adjusted for birthweight, gestation and gender were significantly (P less than 0.05) better in larger centres. Oxygen requirement was assessed at 28 days of age, 36 weeks equivalent gestation and 84 days of age, when 38.6, 23.1 and 13.8% of infants, respectively, were being treated with oxygen. To examine the joint effects of predictor variables on oxygen requirement at each age, the data were analysed using multiple logistic regression methods. At 28 days, lower birthweight, shorter gestation, respiratory distress syndrome (all P less than 0.0001), and gender and hospital principally caring for the infant (both P less than 0.05) were significantly associated with treatment with oxygen. In comparison with other studies, New Zealand appears to have a relatively high rate of chronic lung disease. We speculate that a contributing factor may be the small size of some regional neonatal units.     

Catch-up growth in Malawian babies, a longitudinal study of normal and low birthweight babies born in a malarious endemic area

INTRODUCTION: Infant growth has not been studied in developing countries in relation to maternal factors related to malaria in pregnancy and maternal illiteracy. OBJECTIVE: To describe growth patterns in infants with low and normal birthweight and determine maternal risk factors for infant undernutrition. METHODS: Babies born in a rural district of southern Malawi were recruited. An infant cohort was selected on the basis of low or normal birthweight. Weight and length were recorded at birth and at 4-weekly intervals until at 52 weeks after birth. Maternal characteristics at first antenatal attendance and delivery were obtained. Odds ratios in univariate analysis were adjusted for birthweight. Factors included in the multivariate regression included maternal illiteracy, season of birth, maternal iron deficiency and number of infant illness episodes. RESULTS: Low birthweight infants were shorter and lighter throughout infancy than either normal birthweight or international reference values. At 12 months, placental or peripheral malaria at delivery (adjusted odds 1.8; 1.0, 3.1), number of infant illness episodes (AOR = 2.1; 1.2, 3.6) and maternal illiteracy (AOR = 2.7; 1.5, 4.9) were independently associated with low weight for age. Maternal short stature (AOR = 1.8; 1.1. 3.2), male sex (AOR = 2.4; 1.4, 4.1), number of infant illness episodes (AOR = 2.6; 1.5, 4.4), and birth in the rainy season (2.1; 1.2, 3.7) were independently associated with stunting. Placental or peripheral malaria at delivery (AOR = 2.2; 1.1, 4.4) and number of illness episodes (AOR = 2.2; 1.1, 4.5) were independently associated with thinness. CONCLUSION: Malaria during pregnancy and maternal illiteracy are important maternal characteristics associated with infant undernutrition. Innovative health/literacy strategies are required to address malaria control in pregnancy in order to reduce the magnitude of its effects on infant undernutrition.     

INFANT MORTALITY: Causes of Death During the First Year of Life in a Five-year Series

In the years 1966–1970 all together 17 805 children were born in Malmo (population about 260000). 141 were stillborns and 172 infants survived at most 6 days, which means a perinatal mortality of 1.74 %, and neonatal mortality within 6 days of 0.97 %. The infantmortality was 1.3%. These figures agree closely with Swedish vital statistics. 5.4% were LBW-infants with a neonatal mortality of 13.3%. 231 infants died during the first year and necropsies were performed in all but 2. The main causes of death were malformations in 65 cases, haemorrhages in 31 and hyaline membranes in 61. In 38.children with a birth weight below 1700 g, post-mortem examination revealed no morphologic changes except immaturity. Diseases of the mother and complications of pregnancy and delivery were more common among mothers of children with low birthweight. The causes of infant mortality in countries with a good standard of living are mainly severe malformations and complications of very low birthweight and short gestation period.     

Risk factors for preterm and small-for-gestational-age babies: a cohort from the Pacific Islands Families Study

AIM: To explore risk factors that are associated with preterm birth and full-term small-for-gestational-age (SGA) birth for a Pacific population. METHODS: Data were gathered from the Pacific Islands Families Study. Mothers of a cohort of 1398 Pacific infants born in South Auckland, New Zealand during 2000 were interviewed when their infants were 6 weeks old. Mothers were questioned regarding maternal health, antenatal care and life-style behaviours. Data regarding birth outcomes were obtained from hospital records. Analyses focused on 1324 biological mothers who gave birth to a singleton and had valid data for birth outcomes. RESULTS: Of 1324 singleton infants, the mean birthweight was 3.60 kg with standard deviation of 0.60 kg. Fifty-two (3.9%) had birthweight less than 2500 g. Ninety-four (7.1%) were born at less than 37 weeks of gestation. Most socio-demographic factors were not associated with poor birth outcomes. Primiparous birth, less frequent attendance of antenatal care and mother's history of high blood pressure were associated with preterm birth and SGA. Smoking during pregnancy increased the odds of having an SGA but not preterm birth. On the other hand, unplanned/unsure pregnancy and prior early pregnancy loss were associated with preterm birth but not SGA. CONCLUSION: Corroborating research conducted with other populations, most of the internationally and nationally recognised risk factors for preterm birth and SGA are also important for Pacific people. Smoking seems to explain more poor birth outcomes in Pacific Islands than in the New Zealand population as a whole.     

Infants admitted to a neonatal intensive care unit: parental psychological status at 9 months

AIM: This paper reports on the 9-month follow-up of parents who had an infant admitted to neonatal intensive care unit (NICU) compared to parents of full-term health infants. The psychological status of the parent groups is compared and factors associated with status change are examined. METHODS: Prospective longitudinal study of random sample of 447 parents (mother and father with an infant admitted to the NICU and 189 parents (mother and father) with term infant not requiring NICU admission. Parents' depression and anxiety symptoms were assessed at infant birth and 9 months later. RESULTS: The increased levels of depression and anxiety symptoms evident in NICU parents after their infant's birth were no longer apparent by 9 months. Higher initial symptom severity and perceived quality of the couple relationship were most commonly associated with improvement. Other factors related to symptoms change were number of baby hospitalizations for fathers and being in the NICU, age and living with the infant's father or mother. CONCLUSION: For the majority of parents having an infant admitted to the NICU does not result in ongoing psychological distress.     

母体高尿酸血症对妊娠结局和新生儿合并症影响的回顾性巢式病例对照研究

背景：高尿酸血症（HUA）患病率逐年增高,不仅与痛风、尿酸盐肾病和肾结石有关,还与内分泌代谢、心脑血管等系统疾病的发生和发展有关。 目的：探讨孕母妊娠晚期血尿酸水平与不良妊娠结局、新生儿尿酸水平及新生儿合并症的关系。 设计：回顾性巢式病例对照研究。 方法：以2020年1~12月在北京大学人民医院产检的孕母为队列人群,根据孕母妊娠晚期血尿酸水平分为HUA组和非HUA组,比较两组妊娠结局和新生儿临床结局。根据孕母妊娠晚期血尿酸水平（μmol·L-1）分为低浓度（<360）、中浓度（~420）和高浓度（>420）,采用线性回归和Logistic 回归模型分析孕母血尿酸水平与早产、低出生体重、小于胎龄儿的关系。孕母妊娠晚期尿酸值及新生儿生后24 h尿酸值相关性分析采用Spearman秩相关分析。 主要结局指标：孕母血尿酸水平与早产、低出生体重和小于胎龄儿的关系。 结果：共纳入孕母2 397例（新生儿2 581例）,HUA组216例（9.0%）,非HUA组2 181例。HUA组孕母所生新生儿出生体重低于非HUA组（2 925 g vs 3 260 g,P<0.001）,差异均有统计学意义;而早产（18.5% vs 8.9%）、低出生体重（23.1% vs 7.1%）、小于胎龄儿（29.2% vs 10.6%）和转儿科比例（19.9% vs 11.1%）均高于非HUA组,差异均有统计学意义（P<0.001）。尿酸水平高浓度组孕母分娩的新生儿出生体重较低浓度组低54.0 g（95%CI：-106.5~-1.6,P=0.043）,发生早产的风险增加74%（OR=1.74,95%CI：1.08~2.8,P=0.023）,发生小于胎龄儿的风险增加85%（OR=1.85,95%CI：1.26~2.73,P=0.002）。新生儿生后24 h内尿酸水平与孕母妊娠晚期尿酸水平呈中等相关（r=0.613,P=0.000）。两组早产儿合并症差异无统计学意义。 结论：母体妊娠晚期HUA与早产、低出生体重、小于胎龄儿的发生相关。     

Perinatal outcome for small-for-gestational-age infants from an unselected, area-based population

From an unselected area-based population, where a screening programme for detection of small-for-gestational-age (SGA) infants was in use, the obstetrical and neonatal management of all SGA infants (birth wt. less than or equal to -2 S.D. of the normal mean) was studied. During 1980, there were 3038 singletons born at the University Hospital in Uppsala. The perinatal mortality was 0.6% (17 infants). Three stillborn infants were assessed as SGA, even when gestational age was estimated from the last occasion when fetal heart sounds were registered. Out of a total of 27 live-born SGA infants (0.9%), 19 were suspected and supervised antenatally. All SGA infants were admitted to the neonatal ward. One infant suffered from the fetal alcohol syndrome and one preterm infant died after 11 days due to septicaemia after abdominal surgery. The remaining 25 SGA infants escaped severe neonatal problems and were discharged from the hospital around the time of expected delivery. It is concluded that once an SGA pregnancy is identified and supervised, the risk of intrauterine death is minimized and that the neonatal period generally is uncomplicated for the normally shaped and adequately cared-for SGA infant.     

Factors adversely associated with breast feeding in New Zealand

Control data from 1529 infants studied in a multicentre case-control study of sudden infant death in New Zealand were analysed to identify factors that might hinder the establishment and duration of breast feeding. Although 1300 infants (85%) were exclusively breast-fed at discharge from the obstetric hospital, this fell to 940 (61%) by 4 weeks. Logistic regression was used to identify factors that might adversely influence breast feeding ‘at discharge’,‘at 4 weeks’ and the overall ‘duration’ of breast feeding. When adjusted for confounding factors, not exclusive breast feeding ‘at discharge’ was significantly associated with: twin pregnancy, being a Pacific Islander, mother not bedsharing, subsequent dummy use, birthweight less than 2500g, heavy maternal smoking, not attending antenatal classes and mother less than 20 years old at first pregnancy. Mothers smoking more than 20 cigarettes a day were nearly twice as likeiy to not exclusively breast feed on discharge compared to those who did not smoke. A ‘dose response’ was apparent with the heaviest smokers having the least likelihood of establishing exclusive breast feeding. Being exclusively breast-fed at discharge but not ‘at 4 weeks’ was associated with: twin pregnancy, admission to a neonatal intensive care unit, subsequent dummy use and not being married. A shorter overall ‘duration’ of breast feeding was associated with maternal smoking, subsequent dummy use, mother not bedsharing, twin pregnancy, mother less than 20 years old at first pregnancy, low occupational status and not attending antenatal classes. These effects persisted when social and demographic factors, including birthweight, were taken into account. This study showed that 31% of New Zealand women had smoked during their pregnancy. A concerted effort to achieve smokefree pregnancies would not only directly improve the health of mother and child but may enhance both the initiation and duration of breast feeding. The influence on the duration of breast feeding of both dummy usage and the mother sharing the bed with her infant needs to be explored further, as a causal relationship cannot be established from these data.     

Visits by the family to the neonatal intensive care unit

AIM: To investigate visiting frequency of family members, including mother, father, siblings and grandparents and associated factors during hospitalisation of preterm infants. METHODS: The study included all premature (< 37 weeks) infants born in Tampere University Hospital in 1997-1998 admitted to the neonatal intensive care unit (NICU) with a birth weight less than 2500 g (n = 210). Maternal and infant data and visits made by family members were compiled from the infants' hospital records. RESULTS: The length of the infants' hospitalisation varied from 2 to 133 days (median 26, quartiles 19, 45). Mothers visited the NICU on average 6.7 days/week; fathers 4.8 days/week. Mothers visited less frequently the lower the gestational age and the longer the distance between home and hospital. Fathers visited less frequently if distance from home to hospital was longer and if the infant had siblings. A total of 92% of siblings and 80% of grandparents visited the hospital. CONCLUSIONS: The results showed active visiting by the parents in the NICU. A lower gestational age was associated with lower visiting frequency for mothers. In contrast, more practical limitations such as geographical distance and other children to be taken care of had greater effect on the visiting frequency for fathers.     

Prediction of transfusions in extremely low-birthweight infants in the erythropoietin era

BACKGROUND: The purpose of the present paper was to detect the clinical factors most predictive of red blood cell (RBC) transfusion in extremely low-birthweight (ELBW) infants in the recombinant human erythropoietin era. METHODS: Between 1995 and 2000, 66 ELBW infants were admitted to a level III neonatal intensive care unit. Fifty-four of 66 infants were eligible for enrollment in the present study. Infants were treated with erythropoietin 200 IU/kg per dose s.c. twice a week with 4-6 mg/kg per day iron supplement. RESULTS: The mean gestational age and birthweight were 26.5 +/- 2.1 weeks and 776 +/- 134 g, respectively. Ten of 54 ELBW infants (18.5%) died during the first 21 days. Eight of 10 dead infants (80.0%) and 27 of 44 surviving infants (61.4%) received one or more RBC transfusions. The overall requirement for RBC transfusions in the surviving infants was 3.0 +/- 3.2 per infant/hospital course (range: 0-9) . There were significant differences in gestational weeks, birthweight, initial hemoglobin value, 5 min Apgar score, phlebotomy loss, phlebotomy loss/birthweight, duration of mechanical ventilation, duration of oxygen supplement, and incidence of both intraventricular hemorrhage and chronic lung disease between the transfused and non-transfused group. The predictive variables, initial hemoglobin level (odds ratio [OR] 2.61; 1 g/dL), birthweight (OR 3.00; 100 g), and gestational week (OR 1.89; 1 week), were found to be most predictive for transfusion on logistic regression analysis. CONCLUSION: ELBW infants are still the population at greatest risk for repeated blood transfusions after introduction of erythropoietin treatment. If labor develops, it is often impossible to extend the pregnancy period, therefore efforts should be made to increase hemoglobin level at birth.     

Preterm birth in Sweden: What are the average lengths of hospital stay and the associated inpatient costs?

AIM: To provide estimates of the first-year length of stay and inpatient costs of Swedish infants admitted for neonatal care by week of gestation and by birthweight; and to provide estimates of the length of stay and inpatient costs of delivering mothers during the ante- and postpartum period by week of gestation and birthweight of the infant. METHODS: Population-based registry study covering all live singleton deliveries in Sweden between 1998 and 2001 (n=336 136). First-year hospitalizations of infants admitted for neonatal care 0-6 d after birth (n=24 583) were tracked, as were hospitalizations of mothers for whom the date of admission lay+/-1 mo from the date of delivery. Monetary values were assigned to each hospitalization using the Nord-DRG classification system. RESULTS: On average, preterm infants (GA < 37 wk) had first-year lengths of stay roughly four times as long as full-term infants admitted for neonatal care (30 d vs 8 d, p<0.0001). The average first-year length of stay of the extremely immature infants (GA 22-25 wk) was more than six times as long that of infants born at 34-36 wk (108 d vs 17 d, p<0.0001). Mothers delivering preterm had an average length of stay slightly more than twice as long (p<0.0001) as that of mothers of full-term infants during the ante- and postpartum period. CONCLUSION: The estimated lengths of stay and costs may serve as reference values for a Swedish setting.     

Transient hypothyroxinaemia associated with developmental delay in very preterm infants.

In 563 surviving very preterm (less than 32 weeks gestational age) and/or very low birthweight (less than 1500 g) infants the relationship between neonatal thyroxine concentration and psychomotor development at 2 years of age (corrected for preterm birth) was studied. A significant association was found between low neonatal thyroxine concentration and a negative score on the three milestones of development. These findings do not support the view that transient hypothyroxinaemia in preterm infants is harmless.     

Short-term outcome of mechanically ventilated infants weighing more than 2499 g at birth: A population based study*

Abstract: Very little data exist describing the neonatal outcome of infants of birthweight 2500 g or more who require mechanical ventilation. Our aim was to collect population-based data on such infants in New South Wales (NSW), and to monitor their neonatal morbidity, mortality to 1 year of age and the associated risk factors. The study group (NICUS infants) comprised all 341 infants weighing >2499 g who were admitted to the seven neonatal intensive care units in New South Wales and mechanically ventilated for 4 h or more between 1 January and 31 December, 1987. Two groups of infants emerged: those who were preterm and mostly had hyaline membrane disease, and term and post-term infants for whom the most common problem was ‘perinatal asphyxia’. The most important factors associated with dying were a birthweight of over 3499 g (OR = 2.6; CI 1.03–6.6) and a 1 min Apgar score <4 (OR = 4.8; C11.4–16.9). Study group mothers were significantly more likely than all NSW mothers to have had a spontaneous abortion in the previous pregnancy (P<0.01), a pre-existing medical condition or an obstetric complication in this pregnancy, or a Caesarean section for this delivery (P<0.001). This is the first population-based study of high-risk neonates without congenital anomalies to clearly document the worsening prognosis associated with a birthweight over 3499 g. Further research should be directed towards identifying prenatal and perinatal factors which might minimize the morbidity and mortality in this group of babies.     

SGA subtypes and mortality risk among singleton births

OBJECTIVES: To determine whether early mortality (first year of life) risks among small for gestational age (SGA) neonates were similar regardless of SGA subtype based on three chronological classifications (term, preterm and post-term). STUDY DESIGN: Retrospective cohort study on all singleton live births in the United States from 1995 to 1999 inclusive. Adjusted risk estimates were computed from logistic regression models using non-SGA infants as the referent. RESULTS: When SGA infants were compared as a homogeneous entity to non-SGA infants, the risks for infant, neonatal and post-neonatal mortality were significantly greater in SGA infants [AOR (adjusted odds ratio)=3.0, 95% CI (confidence interval)=2.9-3.0 for infant mortality; AOR=3.2, 95% CI=3.1-3.2 for neonatal mortality; and AOR=2.6, 95% CI=2.6-2.7 for post-neonatal mortality]. However, heterogeneity existed in terms of mortality risk thresholds across SGA babies. The most remarkable risk magnitude was observed among preterm SGA infants [infant mortality AOR=13.8, 95% CI=13.6-14.1; neonatal death AOR=17.4, 95% CI=17.0-17.7; and post-neonatal death AOR=7.4, 95% CI=7.1-7.6]. The adjusted odds ratio for term and post-term SGA infants were comparable regardless of the period during infancy, and were much less than those observed for preterm SGA infants. CONCLUSIONS: SGA is a heterogeneous disease in terms of prognosis for survival. Preterm SGA infants bear an extremely high risk for mortality during infancy, and counseling of affected parents should reflect this risk divergence.     

Evaluation of fetal and maternal genetic variation in the progesterone receptor gene for contributions to preterm birth

Progesterone plays a critical role in the maintenance of pregnancy and has been effectively used to prevent recurrences of preterm labor. We investigated the role of genetic variation in the progesterone receptor (PGR) gene in modulating risks for preterm labor by examining both maternal and fetal effects. Cases were infants delivered prematurely at the University of Iowa. DNA was collected from the mother, infant, and father. Seventeen single nucleotide polymorphisms (SNP) and an insertion deletion variant in PGR were studied in 415 families. Results were then analyzed using transmission disequilibrium tests and log-linear-model-based analysis. DNA sequencing of the PGR gene was also carried out in 92 mothers of preterm infants. We identified significant associations between SNP in the PGR for both mother and preterm infant. No etiologic sequence variants were found in the coding sequence of the PGR gene. This study suggests that genetic variation in the PGR gene of either the mother or the fetus may trigger preterm labor.