Effects of calcium supplementation during pregnancy on maternal, fetal and birth outcomes

Gestational hypertensive disorders are the second leading cause of maternal death worldwide. Epidemiological and clinical studies have shown that an inverse relationship exists between calcium intake and development of hypertension in pregnancy. The purpose of this review was to evaluate preventive effect of calcium supplementation during pregnancy on gestational hypertensive disorders and related maternal and neonatal morbidity and mortality. A literature search was carried out on PubMed, WHOLIS, PAHO and Cochrane Library. Only randomised trials were included in the review. Data were extracted into a standardised Excel sheet. Primary outcomes were pre-eclampsia, preterm birth and birthweight. Other neonatal outcomes such as neonatal mortality, small-for-gestational age and low birthweight were also evaluated. A total of 15 randomised controlled trials were included in this review. Pooled analysis showed that calcium supplementation during pregnancy reduced risk of pre-eclampsia by 52% [relative risk (RR) 0.48; 95% confidence interval (CI) 0.34, 0.67] and that of severe pre-eclampsia by 25% (RR 0.75 [95% CI 0.57, 0.98]). There was no effect on incidence of eclampsia (RR 0.73 [95% CI 0.41, 1.27]). There was a significant reduction for risk of maternal mortality/severe morbidity (RR 0.80 [95% CI 0.65, 0.97]). Calcium supplementation during pregnancy was also associated with a significant reduction in risk of pre-term birth (RR 0.76 [95% CI 0.60, 0.97]). There was an extra gain of 85 g in the intervention group compared with control (mean difference 85 g [95% CI 37, 133]). There was no effect of calcium supplementation on perinatal mortality (RR 0.90 [95% CI 0.74, 1.09]). There was a statistically non-significant increased risk of urolithiasis in the intervention group compared with control (RR 1.52 [95% CI 0.06, 40.67]). In conclusion, calcium supplementation during pregnancy is associated with a reduction in risk of gestational hypertensive disorders and pre-term birth and an increase in birthweight. There is no increased risk of kidney stones.     

Maternal ethnicity and pre-eclampsia in New York City, 1995-2003

Studies on ethnic differences in the risk of pre-eclampsia are limited. We linked birth records for 902,460 singleton births for the period 1995-2003 in New York City with hospital discharge data to evaluate the association between ethnicity and the risk of pre-eclampsia and compare risks between US-born and foreign-born women. Logistic regression models adjusted for maternal age, maternal education, parity, self-reported pre-pregnancy maternal weight, smoking during pregnancy and year of delivery were used to compare each ethnic group with non-Hispanic White women. The prevalence of pre-eclampsia in this study population was 3.2%. Among the major ethnic groups considered in our study, East Asian women had the lowest risk of pre-eclampsia (1.4%) and Mexican women had the highest risk (5.0%). Compared with non-Hispanic White women, there was a slightly decreased risk for East Asian women (adjusted OR = 0.8, [95% CI 0.7, 0.8]), similar risk for North African women (adjusted OR = 1.1, [95% CI 0.9, 1.3]), and increased risk for all other major ethnic groups (adjusted ORs: 1.3, 2.9), with the highest risk for Mexican women (adjusted OR = 2.9, [95% CI 2.7, 3.1]). No difference in risks was observed for US- vs. foreign-born women with the exception that foreign-born South-East Asian and Pacific Islanders had an increased risk of pre-eclampsia (adjusted OR = 1.8, [95% CI 1.0, 3.1]) relative to those born in the US. We concluded that there was ethnic heterogeneity in the development of pre-eclampsia among women in New York City and that Asian subgroups should be examined separately in future studies on ethnicity. Our results should contribute to screening for pre-eclampsia taking ethnic variation into account, and may help to suggest leads for the study of the aetiology of the condition.     

Chronic hypertension, cigarette smoking, and abruptio placentae.

We investigated the importance of maternal hypertension and cigarette smoking, and their interaction, as risk factors for abruptio placentae, using Massachusetts birth certificate data for 1987-1988. We used multiple logistic regression procedures to model data from 943 abruptio placentae cases and 10,648 randomly selected births. Risk of abruption was associated with a history of chronic hypertension (adjusted OR = 2.3, 95% CI: 1.5-3.5) and cigarette smoking during pregnancy (adjusted OR = 1.7, 95% CI: 1.5-2.0). There was also evidence of interaction between chronic hypertension and cigarette smoking. The hypoxemia that results from exposure to cigarette smoke and the alterations in uterine blood flow that result from hypertension may lead to placental lesions that cause abruption.     

Effect of smoking and alcohol use during pregnancy on the occurrence of low birthweight in a farming region in South Africa

The aim of this case-control study was to determine the risk factors for low birthweight in a farming region in South Africa, with particular attention to maternal alcohol use and smoking, both independently and in combination. Data collection was via structured postpartum interviews and review of antenatal and delivery records. The study setting was a regional referral hospital in a farming region. The study subjects were 200 infants with birthweight < 2500 g (cases) and 200 unmatched control infants of normal weight born during the same period as the cases. The outcome measure was low birthweight, i.e. infant birthweight <2500 g. Results showed the contribution of term low birthweight (as a measure of intrauterine growth retardation) to the total low-birthweight incidence was almost 50%, indicating a substantial intrauterine growth retardation component in this population. Sociodemographic factors were not as predictive of low birthweight in this predominantly low income population. Smoking (adjusted OR 2.67, [95% CI 1.69, 4.20]) was the strongest life style-related predictor of low birthweight. The alcohol low-birthweight relationship was not significant when adjusted for smoking status (crude OR 2.15, [95% CI 1.37, 3.39]; adjusted OR 1.32, [95% CI 0.80, 2.20]). However, there appeared to be an interaction with combined use of these two substances during pregnancy that increased the risk of low birthweight (adjusted OR increased to 4.24, [95% CI 1.01, 17.76]. It is clear that life style factors such as smoking and drinking are contributing to the occurrence of low birthweight in the target region. A comprehensive health promotion programme needs to be implemented as an integral part of antenatal and family planning services, to reduce smoking and drinking by women in this community.     

Prenatal risk factors for cryptorchidism: a record linkage study

Using data from the Oxford Record Linkage Study (ORLS), we conducted a case–control study to examine prenatal risk factors for cryptorchidism. We identified 1449 boys born during 1970–86 for whom there was a record of an orchidopexy during 1970–87. Up to eight controls were matched to each case on year of birth and hospital or place of delivery. For each boy and his mother we extracted abstracts of maternity and general hospital records from the ORLS. Low birthweight (trend P  < 0.001), low social class (trend P  < 0.001), breech presentation (relative risk 1.67; 95% confidence interval [CI] 1.16, 2.41), pre-eclampsia (1.17 [1.00, 1.37]), artificial feeding (1.22 [1.04, 1.45]) and episiotomy (1.13 [1.00, 1.27]) were identified as independent risk factors for cryptorchidism. Gestational age was not independently associated with cryptorchidism after adjusting for birthweight ( P  = 0.33), and this observation suggested that some cryptorchid boys may have suffered from intra-uterine growth retardation. Low birthweight, breech presentation and pre-eclampsia may have in common poor placental function and impaired fetal growth, which may be causes of cryptorchidism.     

Book review

Previous studies have suggested a relationship between reproductive history, pregnancy and birth factors, and the risk of neuroblastoma. We conducted a case-control telephone interview study that included a total of 504 children under the age of 19 years with newly diagnosed neuroblastoma identified by two national collaborative clinical trials groups, the Children's Cancer Group and the Pediatric Oncology Group. A total of 504 controls, matched to cases on age, were identified by random digit dialing. Conditional logistic regression was used to estimate the matched odds ratio (OR) and 95% confidence interval (CI) with adjustment for household income, and maternal race and education. In addition, case subgroups defined by age at diagnosis, tumour MYCN oncogene amplification status, and stage were evaluated. A suggestive pattern of increased risk was seen for a greater number of prior pregnancies, history of previous miscarriages and induced abortions, with nearly a twofold increase in risk for two or more prior induced abortions (OR = 1.9, 95% CI [1.0,3.7]). No association was found for the following diseases or conditions during pregnancy: hepatitis, rubella, measles, mumps, chickenpox, mononucleosis, vaccinations, morning sickness, pre-eclampsia, bleeding, proteinuria, anaemia, urinary tract infections, heart disease, kidney disease, liver disease and diabetes. A weak association was found for hypertension during pregnancy. Several labour and delivery factors were related to an increased risk, including threatened miscarriage, anaesthetic during labour (specifically epidural) and caesarean delivery. We found associations between premature delivery (<33 weeks: OR = 1.9, 95% CI [0.7,4.8]), very low birthweight (<1500 g: OR = 2.6, 95% CI [0.7,10.3]) and risk of neuroblastoma. There was no consistent pattern of increased risk found for most factors within subgroups defined by age at diagnosis, stage or MYCN status.     

Pre-eclampsia and premature labour among pregnant wowen with haematuria

The authors conducted a retrospective cohort study of pregnant women to estimate the prevalence and associated risk of adverse pregnancy outcomes among pregnant women with microhaematuria. Between 1 January 1993 and 15 March 1993 at University of Washington Medical Center, 328 consecutive births were identified, and demographic data, medical history, laboratory data and pregnancy outcomes were abstracted from hospital charts. The presence or absence of haematuria was determined in 276/328 cases. Sixteen per cent (44/276) of the women were found to have haematuria. Those with haematuria were at increased risk of developing pre-eclampsia (odds ratio [OR] = 9.5, 95% confidence interval [CI] 3.1, 28.2) and premature labour (OR = 3.8, 95% CI 1.5, 9.7). These associations persisted after controlling for age, race, and urinary tract infection (UTI) (pre-eclampsia OR=9.1, 95% CI 2.5, 33.7; premature labour OR = 4.2, 95% CI 1.2, 15.3). Infants of women with haematuria were at a non-significantly increased risk of low Apgar scores (OR = 2.8, 95% CI 0.7, 11.9) and low birthweight (OR=1.9, 95% CI 0.7, 4.7). In this observational study, microscopic haematuria was prevalent among pregnant women and was independently associated with an increased risk of adverse maternal complications.     

Risks of repeated miscarriage

There is a lack of well-designed epidemiological studies of possible risk factors for repeated miscarriage. In this Swedish population-based case-control study, we investigated the association between sociodemographic and anthropometric factors, obstetric history and life-style factors, with respect to the risks of first-trimester repeated miscarriage. Information on maternal characteristics was collected through in-person interviews. Plasma blood samples were analysed for cotinine and folate concentrations. Adjusted odds ratios (OR) with 95% confidence interval [CI] were used to estimate the relative risk of repeated miscarriage. The risks of repeated miscarriage were increased for women aged > or = 35 years (adjusted OR 2.9 [95% CI 1.4, 5.8]), as well as for women aged < or = 24 years (OR 2.8 [95% CI 1.1, 6.8]). Women with a history of at least one preceding miscarriage prior to the two index pregnancies, women reporting prolonged time to conceive, and women with a history of myoma, faced a more than fourfold increased risk of repeated miscarriage. Smokers were at an increased risk of repeated miscarriage (OR 2.1 [95% CI 1.1, 4.1]). Among non-smoking women with high caffeine intake, there was an increased risk of repeated miscarriage, whereas there was no such association among smokers. Low plasma folate levels were not associated with increased risks.     

重度子痫前期并发胎盘早剥46例临床分析

目的:探讨重度子痫前期并发胎盘早剥患者的临床特征及母婴预后。方法:以重度子痫前期并发胎盘早剥46例为观察组,同期重度子痫前期未并发胎盘早剥的383例为对照组,比较临床特征及母婴结局。结果:观察组分娩孕周(33.7±4.0)周明显小于对照组(35.6±3.8)周,差异有统计学意义(P<0.05)。观察组产前出血、强直宫缩、胎儿窘迫胎死宫内高于对照组,观察组白细胞、D-二聚体高于对照组,血红蛋白、血小板、纤维蛋白原低于对照组,观察组尿蛋白水平高于对照组,差异均有统计学意义(P<0.05),观察组出生低体重、新生儿窒息或死亡、子宫胎盘卒中、产后出血均高于对照组(P<0.05)。观察组中入院即诊断胎盘早剥者较入院后发现者早剥面积大、新生儿评分低、产后出血多,差异有统计学意义(P<0.05)。结论:早发型重度子痫前期患者较易发生胎盘早剥,重视胎盘早剥发生的早期临床表现,及时进行血常规、凝血功能、尿蛋白水平及B超检测,及时发现、早期处理胎盘早剥以改善母儿预后。     

Placental abruption and perinatal death

Studies of risk factors for abruptio placentae (AP) are partly conflicting and studies of risk factors for perinatal death in these pregnancies are scarce. Using the population-based Swedish Birth Registry from 1987 to 1993, we were able to study these risks in 795,459 singleton pregnancies. Logistic regression analysis was used to estimate odds ratios (OR) for risk of AP and risk of perinatal death in pregnancies with and without AP. Risk factors for AP were: age, primiparity, high parity, not cohabiting with infant's father, low education, smoking, infertility, pregestational diabetes, essential hypertension, pregnancy-induced hypertensive diseases, preterm premature rupture of membranes, preterm birth and small-for-gestational-age (SGA) births. Risk factors for perinatal death in pregnancies with placental abruption were smoking (1--9 and > or =10 cigarettes/day; OR 1.4 and 1.7 respectively), severe pre-eclampsia (OR 2.0) and SGA (OR 1.9), whereas in pregnancies without abruption, risks were also increased in maternal age > or =35 years, primiparity, infertility, essential hypertension and pregestational diabetes. These findings support the theory that, in cases of AP, a general impairment of the placenta and/or a defect placentation may be fatal.     

Pregnancy outcomes in smokers who develop pre-eclampsia

Maternal smoking reduces the risk of pre-eclampsia, but has been reported to increase the risk of adverse outcomes related to the disease. We used data from the trial of Calcium for Pre-eclampsia Prevention (CPEP) to explore whether clinical manifestations of pre-eclampsia were altered by maternal smoking. CPEP was a randomised study of 4589 nulliparous women conducted in five US medical centres. Smoking history was obtained at study enrolment and women were monitored for the development of hypertension, proteinuria, and other medical complications. Among pre-eclamptic women (n=274), the risk of severe disease was not elevated in smokers (adjusted odds ratio 0.87 [95% confidence interval (CI) 0.30, 2.51]). Compared with non-smokers, gestational age (days, +/-SE) at onset of pre-eclampsia was not reduced in smokers (264.8 +/- 1.5, and 268.2 +/- 5.5, respectively, P=0.48). The smoking-attributable deficit in birthweight was not increased in pre-eclamptic women compared with normotensive women (97 g [95% CI -49, 244] and 185 g [95% CI 141, 229] respectively). In conclusion, among women who developed pre-eclampsia, smoking during pregnancy was not associated with disease severity. We found no evidence that pre-eclampsia and smoking act synergistically to restrict fetal growth.     

Prenatal and intrapartum events and sudden infant death syndrome

The purpose of this study was to evaluate specific pregnancy and labour and delivery events that may increase the risk of sudden infant death syndrome (SIDS). A matched case-control study was conducted in five counties in southern California, using California death certificate records. The sample consisted of 239 Caucasian, African-American, Hispanic and Asian mothers of SIDS infants and 239 mothers of control infants matched on sex, race, birth hospital and date of birth. Mothers participated in a detailed telephone interview and provided access to obstetric and paediatric records. More case than control mothers reported a family history of anaemia (OR=2.12, P < 0.001). Placental abruptions were strongly associated with SIDS (unadjusted OR=7.94, [95% CI 1.34,47.12]). There was an increased risk of SIDS death associated with maternal anaemia during pregnancy (OR=2.51, [95% CI 1.25,5.03]), while simultaneously adjusting for maternal smoking during pregnancy, maternal years of education and age, parity, infant birthweight, gestational age, medical conditions at birth, infant sleep position and post-natal smoking. Interactions of anaemia and prenatal smoking as well as anaemia and post-natal smoking were not statistically significant. There were no other statistically significant differences between case and control mothers for pregnancy conditions, labour and delivery events (e.g. caesarean sections, anaesthesia, forceps) or newborn complications (e.g. nuchal cord, meconium aspiration). Anaemia and placental abruptions were significantly associated with an increased risk of SIDS; both are circumstances in which a fetus may become hypoxic, thereby compromising the subsequent growth, development and ultimate survival of the infant.     

Effect of n-3 long-chain polyunsaturated fatty acid intake during pregnancy on maternal, infant, and child health outcomes: a systematic review

Evidence from observational studies and randomised trials has suggested a potential association between intake of n-3 long-chain polyunsaturated fatty acids (LCPUFA) during pregnancy and certain pregnancy and birth outcomes. Marine foods (e.g. fatty sea fish, algae) and select freshwater fish contain pre-formed n-3 LCPUFA, which serve as precursors for bioactive molecules (e.g. prostaglandins) that influence a variety of biological processes. The main objective of this analysis was to summarise evidence of the effect of n-3 LCPUFA intake during pregnancy on select maternal and child health outcomes. Searches were performed in PubMed, EMBASE, and other electronic databases to identify trials where n-3 LCPUFA were provided to pregnant women for at least one trimester of pregnancy. Data were extracted into a standardised abstraction table and pooled analyses were conducted using RevMan software. Fifteen randomised controlled trials were eligible for inclusion in the meta-analysis, and 14 observational studies were included in the general review. n-3 LCPUFA supplementation during pregnancy resulted in a modest increase in birthweight (mean difference = 42.2 g; [95% CI 14.8, 69.7]) and no significant differences in birth length or head circumference. Women receiving n-3 LCPUFA had a 26% lower risk of early preterm delivery (<34 weeks) (RR = 0.74; [95% CI 0.58, 0.94]) and there was a suggestion of decreased risk of preterm delivery (RR = 0.91; [95% CI 0.82, 1.01]) and low birthweight (RR = 0.92; [95% CI 0.83, 1.02]). n-3 LCPUFA in pregnancy did not influence the occurrence of pre-eclampsia, high blood pressure, infant death, or stillbirth. Our review of observational studies revealed mixed findings, with several large studies reporting positive associations between fish intake and birthweight and several reporting no associations. In conclusion, n-3 LCPUFA supplementation during pregnancy resulted in a decreased risk of early preterm delivery and a modest increase in birthweight. More studies in low- and middle-income countries are needed to determine any effect of n-3 LCPUFA supplementation in resource-poor settings, where n-3 PUFA intake is likely low.     

Risk factors for isolated talipes equinovarus in Western Australia, 1980-1994

A case-control study based on routinely collected data for a West Australian (WA) cohort of births born 1980-94 inclusive was used to identify potential risk factors for the foot deformity isolated talipes equinovarus. Race and sex were identified as risk factors and risk modifiers of the condition in WA infants. In comparison with their female counterparts, Aboriginal males were at greater risk of the deformity than Caucasian males (odd ratio [OR] 7.15, 95% confidence interval [CI] 2.68, 21.12 vs. OR 1.63, 95% CI 1.24, 2.15 respectively). Sex-specific risk estimates of the deformity showed that Aboriginal males were at more than four times the risk of Caucasian males (OR 4.27, 95% CI 2.30, 8.25 respectively), but the risk amongst Aboriginal females was not dissimilar to the risk amongst Caucasian females (OR 1.12, 95% CI 0.49, 2.45). Intrauterine constraint of the fetus was not found to be an important contributing factor to the deformity after accounting for the effect of all risk factors modelled in multivariable analyses. Indicators of intrauterine constraint including prolonged gestation, high infant birthweight, young maternal age (< 20 years) and breech presentation were not associated with excess numbers of isolated talipes equinovarus cases. Limited numbers of cases associated with other indicators of intrauterine constraint, including the specific categories of short maternal stature and a twin pregnancy prevented definitive conclusions regarding their association with the deformity. Improved data quality for gestational age estimates and oligohydramnios status are required before determining the prenatal risk impact of season of conception and of reduced amniotic fluid levels, respectively, on the occurrence of the deformity.     

Disparities in the prevalence of cognitive delay: how early do they appear?

Cognitively delayed children are at risk for poor mental and physical health throughout their lives. The economically disadvantaged and some race/ethnic groups are more likely to experience cognitive delay, but the age at which delays first emerge and the underlying mechanisms responsible for disparities are not well understood. The objective of this study was to determine when sociodemographic disparities in cognitive functioning emerge, and identify predictors of low cognitive functioning in early childhood. Data were from 7308 singleton and 1463 multiple births in the Early Childhood Longitudinal Study‐Birth Cohort (ECLS‐B), a nationally representative cohort of children born in the USA in 2001. Multiple logistic regression analyses examined associations between sociodemographic characteristics and low cognitive functioning at 9 and 24 months, and tested whether gestational and birth‐related factors mediate these associations. Sociodemographic characteristics were statistically significant predictors of low cognitive functioning among singletons at 24 months, including the three lowest quintiles of socio‐economic status [lowest quintile, odds ratio (OR) = 2.7, 95% confidence interval [CI][1.7, 4.1]], non‐white race/ethnicity (African American OR = 1.8 [95% CI 1.3, 2.5], Hispanic OR = 2.3 [95% CI 1.6, 3.2]), and gender (male OR = 2.1, [95% CI 1.7, 2.5]). Gestational and birth characteristics associated with low cognitive function at 9 months included very low and moderately low birthweight (OR = 55.0 [95% CI 28.3, 107.9] and OR = 3.6 [95% CI 2.6, 5.1]), respectively, and very preterm and moderately preterm delivery (OR = 3.6 [95% CI 2.0, 6.7] and OR = 2.4 [95% CI 1.7, 3.5]), respectively, but they had weaker effects by 24 months (ORs for birthweight: 3.7 [95% CI 2.3, 5.9] and 1.8 [95% CI 1.4, 2.3]; ORs for preterm: 1.8 [95% CI 1.1, 2.9] and 0.9 [95% CI 0.7, 1.3]). Results for multiple births were similar. Sociodemographic disparities in poor cognitive functioning emerged by 24 months of age, but were not mediated by gestational or birth characteristics. Further investigation of processes whereby social disadvantage adversely affects development prior to 24 months is needed.     

Prenatal risk factors for Caesarean section. Analyses of the ALSPAC cohort of 12,944 women in England

BACKGROUND: There has been an escalation in Caesarean section rates globally. Numerous prenatal factors have been associated with elective and emergency Caesarean section, some of which may be amenable to change. METHODS: A population-based cohort of 12,944 singleton, liveborn, term pregnancies were used to investigate risk factors for Caesarean section using multivariable logistic regression modelling. Numerous prenatal factors were investigated for their associations with the following outcomes: first, with Caesarean section (both elective and emergency) compared with vaginal delivery (spontaneous and assisted); second, for their associations with elective Caesarean section compared with attempted vaginal delivery; and finally emergency Caesarean section compared with spontaneous vaginal delivery. RESULTS: 11,791 women had vaginal delivery and 1153 had Caesarean section (685 emergency, 468 elective). Non-cephalic (breech) presentation (all Caesareans odds ratio (OR) 36.6, 95% confidence interval (CI) 26.8-50.0; elective Caesarean OR 86.4, 95% CI 58.5-127.8; emergency Caesarean OR 9.58, 95% CI 6.06-15.1) and previous Caesarean section (all Caesareans OR 27.8, 95% CI 20.9-37.0, elective Caesarean OR 54.4, 95% CI 38.4-77.5; emergency Caesarean OR 13.0, 95% CI 7.76-21.7) were associated in all analyses with an increased risk of Caesarean section. Extremes of neonatal birthweight were associated with an increased risk of Caesarean section (all Caesareans and emergency section) compared with vaginal delivery as was increasing neonatal head circumferences. In all analyses increasing maternal age (OR 1.07 per year, 95 % CI 1.04-1.09; OR 1.04 per year, 95 % CI 1.01-1.08; OR 1.11 per year, 95% CI 1.08-1.15) was independently associated with increased odds of Caesarean section. Increasing parity was associated with a decrease in risk for all Caesareans and emergency section (OR 0.63, 95% CI 0.53-0.75 and OR 0.46, 95% CI 0.33-0.63, respectively), as was the outcome of the last pregnancy being a live child. Increasing gestation was independently associated with a decreased risk of both all Caesareans and elective Caesarean (OR 0.86, 95% CI 0.80-0.93 and OR 0.52, 95% CI 0.46-0.58 respectively), whereas diabetes mellitus was associated with increased risk. These variables were not associated with emergency section. However, epidural use was associated with an increased risk of emergency Caesarean (OR 6.49, 95% CI 4.78-8.82) while being in a preferred labour position decreased the risk (OR 0.59, 95% CI 0.49-0.73). CONCLUSIONS: A careful exploration of risk factors may allow us to identify reasons for the increasing rates of Caesarean section and the marked variation between institutions.     

Interventions with vitamins B6, B12 and C in pregnancy

The water-soluble vitamins B6, B12 and C play important roles in maternal health as well as fetal development and physiology during gestation. This systematic review evaluates the risks and benefits of interventions with vitamins B6, B12 and C during pregnancy on maternal, neonatal and child health and nutrition outcomes. Relevant publications were identified by searching PubMed, Popline and Web of Science databases. Meta-analyses were conducted for outcomes where results from at least three controlled trials were available. Potential benefits of vitamin B6 supplementation were reduction in nausea and vomiting, improvement in dental health, and treatment of some cases of anaemia. In meta-analysis based on three small studies, vitamin B6 supplementation had a significant positive effect on birthweight (d = 217 g [95% confidence interval (CI) 130, 304]). Interventions with vitamin C alone or combined with vitamin E did not systematically reduce the incidence of pre-eclampsia, premature rupture of membranes, or other adverse pregnancy outcomes. In meta-analyses, vitamins C and E increased the risk of pregnancy-related hypertension (relative risk 1.10 [95% CI 1.02, 1.19]). Effects of vitamin B6 or C intervention on other neonatal outcomes, including preterm birth, low birthweight, and perinatal morbidity and mortality, were not significant. Data on child health outcomes were lacking. Despite the prevalence of vitamin B12 deficiency amongst populations with limited intake of animal source foods, no intervention trials have evaluated vitamin B12 supplementation before or during pregnancy. In conclusion, existing evidence does not justify vitamin C supplementation during pregnancy. Additional studies are needed to confirm positive effects of vitamin B6 supplementation on infant birthweight and other outcomes. While vitamin B12 supplementation may reduce the incidence of neural tube defects in the offspring based on theoretical considerations, research is needed to support this hypothesis.     

Low birthweight, preterm births and intrauterine growth retardation in relation to maternal smoking

The association between the intensity and duration of cigarette smoking during pregnancy and the frequency of low birthweight, preterm births and intrauterine growth retardation was investigated in a historical cohort. All 5166 livebirths occurring in the city of Pelotas, Brazil, during 1993 were identified and mothers interviewed soon after delivery. Children whose mothers smoked during pregnancy had a birthweight 142 g lower than those of non-smoking mothers. The odds ratio for low birthweight among children of smokers was 1.59 [95% CI 1.30–1.95]. There was no association between smoking and preterm delivery assessed by the Dubowitz score. In relation to intrauterine growth retardation, smoking was associated with an odds ratio of 2.07 [95% CI 1.69–2.53]. There was a direct dose–response association between the number of cigarettes smoked and the risk of growth retardation. Women whose partner smoked were also at higher risk of having a child with growth retardation. All the above results were adjusted for confounding factors. The effect of maternal smoking on low birthweight seems to be attributable to intrauterine growth retardation rather than preterm delivery.     

Determinants of Small for Gestational Age Birth at Term

Background: Being born small for gestational age (SGA) is an indicator of intrauterine growth restriction (IUGR) and later health risks. This study investigated determinants of severe and moderate SGA (respectively, birthweight <3rd percentile and 3rd to <10th percentile for gestational age and sex). Methods: A total of 2195 term pregnancies from a prospective cohort were studied. Prenatal data arose from maternal interview at 10–22 weeks of gestation and perinatal data were collected from hospital charts. Severe and moderate SGA were classified by Canadian population standards. Risk factors for SGA were identified from fitting multivariable logistic regression models. Results: Multivariable associations with severe SGA were: maternal age ≥ 35 [odds ratio (OR) 3.2 [95% confidence interval (CI) 1.4, 6.9]], maternal smoking during pregnancy (OR 5.3 [95% CI 2.4, 11.7]), preeclampsia (OR 4.6 [95% CI 1.6, 13.2]) and threatened preterm labour (OR 3.9 [95% CI 1.3, 11.4]). Primiparity was associated with both severe and moderate SGA with OR 2.4 [95% CI 1.1, 5.1] and OR 1.9 [95% CI 1.3, 2.9] respectively. Underweight pre‐pregnancy body mass index was associated with moderate SGA (OR 2.4 [95% CI 1.2, 5.0]). Inclusion of placental weight, in the final model attenuated the associations. Conclusions: This study demonstrated different determinants for severe and moderate SGA. We speculate that the majority of severe SGA infants are IUGR while moderate SGA infants may be a mixture of IUGR and constitutionally small newborns. This study has also contributed evidence linking preterm labour and SGA as two, potentially related, outcomes of overlapping causal mechanisms reflective of ischaemic placental disease.     

Maternal diet and the risk of hypospadias and cryptorchidism in the offspring

Male genital tract birth defects have been associated in previous studies with several prenatal exposures to environmental and dietary risk factors. The purpose of this study was to explore the association between hypospadias and cryptorchidism, and the dietary habits of an agricultural population in Italy. A population-based case-control study was conducted in the Sicilian Province of Ragusa. Cases (n = 90) and controls (n = 202) included births for the period 1998-2002. Data on dietary habits of the mothers, as well as health-related social, occupational and environmental exposures prior to and during the index birth, were collected through interviews. Adjusted odds ratios (OR) were calculated by logistic regression after adjustment for confounding variables. Increased ORs were observed for mothers of children with hypospadias who, during pregnancy, frequently consumed fish (OR = 2.33 [95% confidence interval (CI) 1.03, 5.31]) and market-purchased fruit (OR = 5.10 [95% CI 1.31, 19.82]). For cryptorchidism, increased risk was observed in mothers consuming liver (OR = 5.21 [95% CI 1.26, 21.50]), and smoked products (OR = 2.46 [95% CI 1.15, 5.29]). For the two malformations pooled together, increased risk was associated with maternal consumption of liver (OR = 4.38 [95% CI 1.34, 14.26]) and with frequent consumption of wine (OR = 1.98 [95% CI 1.01, 3.86]). This study suggests that some maternal dietary factors may play a role in the development of congenital defects of the male reproductive tract. In particular, our data indicate that further research may be warranted on the endocrine-disrupting effects resulting from the bioaccumulation of contaminants (fish, liver), pesticides (marketed fruit, wine) and/or potentially toxic food components (smoked products, wine, liver).