PIP: 43 determinants of low birth weight were analyzed from 895 published papers in the English and French literature from 1970-1984 The assessment was limited to singleton births of women living at sea level with no chronic illness; rare factors and complications of pregnancy were excluded The 43 factors were categorized as genetic and constitutional, demographic and psychosocial, obstetric, nutritional, maternal morbidity during pregnancy, toxic exposure and antenatal care The existence and magnitude of a causal effect on birth weight, gestational age, prematurity and intrauterine growth retardation were determined by a set of methodological standards In developed countries, the most important factor was cigarette smoking, followed by nutrition and pre-pregnancy weight In developing countries the major determinants were racial origin, nutrition, low pre-pregnancy weight, short maternal stature, and malaria Pre-pregnancy weight, prior premature birth or miscarriage, diethylstilbestrol exposure and smoking were major determinants of gestational duration, but the majority of prematurity was unexplained in both developed and developing countries There is a need for future research on the effect of maternal work, prenatal care, and certain vitamin and mineral deficiencies on intrauterine growth, and the effect of genital tract infection, prenatal care, maternal employment, stress and anxiety on prematurity

Determinants of low birth weight: Methodological assessment and meta-analysis

Sponsors asked the IOM's Food and Nutrition Board and the Division of Behavioral and Social Sciences and Education Board on Children, Youth, and Families to review and update the IOM (1990) recommendations for weight gain during pregnancy and recommend ways to encourage their adoption through consumer education, strategies to assist practitioners, and public health strategies.The committee was asked to address the following tasks: 1. Review evidence on the relationship between weight gain patterns before, during, and after pregnancy and maternal and child health outcomes, with particular attention to the prevalence of maternal obesity racial/ethnic and age differences, components of GWG, and implications of weight during pregnancy on postpartum weight retention, maternal and child obesity, and later child health. 2. Within a life-stage framework consider factors in relation to GWG that are associated with maternal health outcomes such as lactation performance, postpartum weight retention, cardiovascular disease, metabolic processes including glucose and insulin-related issues, and risk of other chronic diseases; for infants and children, in addition to low birth weight, consider early developmental impacts and obesity-related consequences (e.g., mental health, diabetes). 3. Recommend revisions to the existing guidelines, where necessary, including the need for specific pregnancy weight guidelines for underweight, normal weight, and overweight and obese women and adolescents and women carrying twins or higher-order multiples. 4. Consider a range of approaches to promote appropriate weight gain, including: individual (behavior), psychosocial, community, health care, and health systems; timing and components of interventions; and ways to enhance awareness and adoption of the guidelines, including interdisciplinary approaches, consumer education to men and women, strategies to assist practitioners to use the guidelines, and public health strategies. 5. Identify gaps in knowledge and recommend research priorities.

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Weight Gain During Pregnancy: Reexamining the Guidelines

Preface Abstract 1. Basis of ICRP Reference Values 2. Summary of Reference Values 3. Embryo and Fetus 4. Total Body 5. Respiratory System 6. Alimentary System 7. Circulatory and Lymphatic Systems 8. Urogenital System 9. Skeletal System 10. Integumentary System 11. Additional Organs and Tissues 12. Pregnant Woman: Anatomical and Physiological Changes 13. Elemental Composition of the Body Reference

Basic anatomical and physiological data for use in radiological protection : reference values

BackgroundZika virus (ZIKV) has been linked to central nervous system malformations in fetuses. To characterize the spectrum of ZIKV disease in pregnant women and infants, we followed patients in Rio de Janeiro to describe clinical manifestations in mothers and repercussions of acute ZIKV infection in infants. MethodsWe enrolled pregnant women in whom a rash had developed within the previous 5 days and tested blood and urine specimens for ZIKV by reverse-transcriptase–polymerase-chain-reaction assays. We followed women prospectively to obtain data on pregnancy and infant outcomes. ResultsA total of 345 women were enrolled from September 2015 through May 2016; of these, 182 women (53%) tested positive for ZIKV in blood, urine, or both. The timing of acute ZIKV infection ranged from 6 to 39 weeks of gestation. Predominant maternal clinical features included a pruritic descending macular or maculopapular rash, arthralgias, conjunctival injection, and headache; 27% had fever (short-term and low-grade). By Jul...

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Zika Virus Infection in Pregnant Women in Rio de Janeiro - Preliminary Report.

OBJECTIVE: To examine the maternal and foetal risks of adverse pregnancy outcome in relation to maternal obesity, expressed as body mass index (BMI, kg/m2) in a large unselected geographical population. DESIGN: Retrospective analysis of data from a validated maternity database system which includes all but one of the maternity units in the North West Thames Region. A comparison of pregnancy outcomes was made on the basis of maternal BMI at booking. SUBJECTS: A total of 287 213 completed singleton pregnancies were studied including 176 923 (61.6%) normal weight (BMI 20–24.9), 79 014 (27.5%) moderately obese (BMI 25–29.9) and 31 276 (10.9%) very obese (BMI≥30) women. MEASUREMENTS: Ante-natal complications, intervention in labour, maternal morbidity and neonatal outcome were examined and data presented as raw frequencies and adjusted odds ratios with 99% confidence intervals following logistic regression analysis to account for confounding variables. RESULTS: Compared to women with normal BMI, the following outcomes were significantly more common in obese pregnant women (odds ratio (99% confidence interval) for BMI 25–30 and BMI≥30 respectively): gestational diabetes mellitus (1.68 (1.53–1.84), 3.6 (3.25–3.98)); proteinuric pre-eclampsia (1.44 (1.28–1.62), 2.14 (1.85–2.47)); induction of labour (2.14 (1.85–2.47), 1.70 (1.64–1.76)); delivery by emergency caesarian section (1.30 (1.25–1.34), 1.83 (1.74–1.93)); postpartum haemorrhage (1.16 (1.12–1.21), 1.39 (1.32–1.46)); genital tract infection (1.24 (1.09–1.41), 1.30 (1.07–1.56)); urinary tract infection (1.17 (1.04–1.33), 1.39 (1.18–1.63)); wound infection (1.27 (1.09–1.48), 2.24 (1.91–2.64)); birthweight above the 90th centile (1.57 (1.50–1.64), 2.36 (2.23–2.50)), and intrauterine death (1.10 (0.94–1.28), 1.40 (1.14–1.71)). However, delivery before 32 weeks' gestation (0.73 (0.65–0.82), 0.81 (0.69–0.95)) and breastfeeding at discharge (0.86 (0.84–0.88), 0.58 (0.56–0.60)) were significantly less likely in the overweight groups. In all cases, increasing maternal BMI was associated with increased magnitude of risk. CONCLUSION: Maternal obesity carries significant risks for the mother and foetus. The risk increases with the degree of obesity and persists after accounting for other confounding demographic factors. The basis of many of the complications is likely to be related to the altered metabolic state associated with morbid obesity.

Maternal obesity and pregnancy outcome: a study of 287 213 pregnancies in London

Male infants have an excessive risk of neonatal death by comparison with females. It has never been clear whether this male disadvantage is due to specific disease processes or is a general biologic feature of being male. In an analysis of 2,735 consecutive newborn autopsies, the ratio of males to females was 1.28:, which differs significantly from the 1.05:1 ratio for all U.S. livebirths. There was a near equal male to female ratio for most disorders in stillborn infants while disorders arising after birth demonstrated a strong male disadvantage. The still-born ratios presumably reflect a predominant maternal influence while birth and removal from the maternal environment uncovers an inherent biologic disadvantage of being male, a disadvantage not selectively related to specific disease processes. This nonspecificity is confirmed by the finding of several disorders in which sex ratios for stillborns are quite different than the ratios recorded for liveborn infants. The sex ratio for liveborn Caucasians was significantly greater than for nonwhites, and the nonpoor had a significantly greater ratio than the poor. About half of these differences appear related to a greater incidence of prenatal bacterial infections in the poor and nonwhites.

Neonatal mortality, the male disadvantage.

• One hundred twenty-five sudden infant death syndrome (SIDS) victims followed up since birth from a large prospective study were compared with matched controls. Some of the future SIDS victims showed evidences of neonatal brain dysfunction including abnormalities in respiration, feeding, temperature regulation, and specific neurologic tests. These abnormalities could not be related to events in labor or delivery. A greater proportion of the future victims were mildly underweight for gestational age. The gestations that produced the SIDS victims were characterized by a greater frequency of mothers who smoked cigarettes and had anemia. The demographic profile of SIDS families proved to be indentical to the profile for families with excessive perinatal mortality. Many of the SIDS victims showed a retardation in postnatal growth prior to death. ( Am J Dis Child 130:1207-1210, 1976)

Sudden Infant Death Syndrome: A Prospective Study

Infants with known chronic hypoxemia before death retained a large proportion of the brown fat cells that are normally replaced by white fat cells after birth. Many of these hypoxemic infants also had an abnormal retention of extramedullary hematopoiesis. These same abnormalities were found in many victims of the sudden infant death syndrome.

https://science.sciencemag.org/content/sci/186/4166/837.full.pdf

Hypoxemia and the Sudden Infant Death Syndrome

Fourteen of 28 sudden-infant-death syndrome (SIDS) victims had an abnormal proliferation of astroglial fibers in their brain stems and an enlarged mass of chromaffin cells in their adrenal medullas. Both of these abnormalities were associated with greater than normal muscle in the small pulmonary arteries, abnormal brown fat retention, and retained extramedullary erythropoiesis. These latter three findings are probably evidences of chronic alveolar hypoventilation and hypoxemia. The brain stem and adrenal abnormalities are probably also secondary to chronic hypoxemia.

Brain-stem and adrenal abnormalities in the sudden-infant-death syndrome.

In order to determine whether pregnancy outcome was altered when women were employed outside their homes, 7,722 pregnancies were analyzed. Gestations were not shortened but newborns of women who worked in the third trimester weighed 150 to 400 gm less than newborns of mothers who remained at home. The growth retardation was greatest when women were underweight pregravid and had a low pregnancy weight gain, when they were hypertensive, or when the work required standing. The growth retardation remained after the data were stratified by race, socioeconomic status, and other maternal factors that commonly influence fetal growth. The frequency of large placental infarcts progressively increased when women continued stand-up work into late gestation. Such infarcts reached a peak of 250/1,000 births after the 37th week of gestation in stand-up workers. Low uteroplacental blood flow is a likely explanation for both the fetal growth retardation and the large placental infarcts.

Richard L. Naeye

Papers

Neonatal mortality, the male disadvantage.

Sudden Infant Death Syndrome: A Prospective Study

Hypoxemia and the Sudden Infant Death Syndrome

Brain-stem and adrenal abnormalities in the sudden-infant-death syndrome.

Working During Pregnancy: Effects on the Fetus