The contribution of low birth weight to infant mortality and childhood morbidity

The low-birth-weight infant remains at much higher risk of mortality than the infant with normal weight at birth. In the neonatal period, when most infant deaths occur, the proportion of low-birth-weight infants, especially those with very low weight, is the major determinant of the magnitude of the mortality rates. Furthermore, differences in low-birth-weight rates account for the higher neonatal mortality rates observed in some groups, particularly those characterized by socioeconomic disadvantages. Much of the recent decline in neonatal mortality can be attributed to increased survival among low-birth-weight infants, apparently as a result of hospital-based services. The application of these services is currently considered cost-effective, although whether this will continue to be true in the future is unclear because of the increased survival of very tiny infants. Although low-birth-weight infants remain at increased risk of both postneonatal mortality and morbidity in infancy and early childhood, the risk is substantially smaller than that of neonatal death. In addition, these adverse later outcomes have not offset the gains achieved in the neonatal period. Nonetheless, the increased survival of high-risk infants raises concern about their future requirements for special medical and educational services and about the stress on their families. Despite increased access to antenatal services, only moderate declines in the proportion of low-birth-weight infants has been observed, and almost no change has occurred in the proportion of those with very low weight at birth. In addition, in many areas of the country the birth-weight-specific neonatal mortality rates are similar for groups at high and low risk of neonatal death. In view of these findings, continuation of the current decline in neonatal mortality and reduction of the mortality differentials between high- and low-risk groups require the identification and more effective implementation of strategies for the prevention of low-weight births.

Stillbirths: rates, risk factors, and acceleration towards 2030

An estimated 2.6 million third trimester stillbirths occurred in 2015 (uncertainty range 2.4-3.0 million). The number of stillbirths has reduced more slowly than has maternal mortality or mortality in children younger than 5 years, which were explicitly targeted in the Millennium Development Goals. The Every Newborn Action Plan has the target of 12 or fewer stillbirths per 1000 births in every country by 2030. 94 mainly high-income countries and upper middle-income countries have already met this target, although with noticeable disparities. At least 56 countries, particularly in Africa and in areas affected by conflict, will have to more than double present progress to reach this target. Most (98%) stillbirths are in low-income and middle-income countries. Improved care at birth is essential to prevent 1.3 million (uncertainty range 1.2-1.6 million) intrapartum stillbirths, end preventable maternal and neonatal deaths, and improve child development. Estimates for stillbirth causation are impeded by various classification systems, but for 18 countries with reliable data, congenital abnormalities account for a median of only 7.4% of stillbirths. Many disorders associated with stillbirths are potentially modifiable and often coexist, such as maternal infections (population attributable fraction: malaria 8.0% and syphilis 7.7%), non-communicable diseases, nutrition and lifestyle factors (each about 10%), and maternal age older than 35 years (6.7%). Prolonged pregnancies contribute to 14.0% of stillbirths. Causal pathways for stillbirth frequently involve impaired placental function, either with fetal growth restriction or preterm labour, or both. Two-thirds of newborns have their births registered. However, less than 5% of neonatal deaths and even fewer stillbirths have death registration. Records and registrations of all births, stillbirths, neonatal, and maternal deaths in a health facility would substantially increase data availability. Improved data alone will not save lives but provide a way to target interventions to reach more than 7000 women every day worldwide who experience the reality of stillbirth.

Maternal overweight and obesity and the risk of congenital anomalies: a systematic review and meta-analysis

CONTEXT

Evidence suggests an association between maternal obesity and some congenital anomalies.

OBJECTIVE

To assess current evidence of the association between maternal overweight, maternal obesity, and congenital anomaly.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, and Scopus (January 1966 through May 2008) were searched for English-language studies using a list of keywords. Reference lists from relevant review articles were also searched.

STUDY SELECTION

Observational studies with an estimate of prepregnancy or early pregnancy weight or body mass index (BMI) and data on congenital anomalies were considered. Of 1944 potential articles, 39 were included in the systematic review and 18 in the meta-analysis. Data Extraction and Synthesis Information was extracted on study design, quality, participants, congenital anomaly groups and subtypes, and risk estimates. Pooled odds ratios (ORs) comparing risk among overweight, obese, and recommended-weight mothers (defined by BMI) were determined for congenital anomaly groups and subtypes for which at least 150 cases had been reported in the literature.

RESULTS

Pooled ORs for overweight and obesity were calculated for 16 and 15 anomaly groups or subtypes, respectively. Compared with mothers of recommended BMI, obese mothers were at increased odds of pregnancies affected by neural tube defects (OR, 1.87; 95% confidence interval [CI], 1.62-2.15), spina bifida (OR, 2.24; 95% CI, 1.86-2.69), cardiovascular anomalies (OR, 1.30; 95% CI, 1.12-1.51), septal anomalies (OR, 1.20; 95% CI, 1.09-1.31), cleft palate (OR, 1.23; 95% CI, 1.03-1.47), cleft lip and palate (OR, 1.20; 95% CI, 1.03-1.40), anorectal atresia (OR, 1.48; 95% CI, 1.12-1.97), hydrocephaly (OR, 1.68; 95% CI, 1.19-2.36), and limb reduction anomalies (OR, 1.34; 95% CI, 1.03-1.73). The risk of gastroschisis among obese mothers was significantly reduced (OR, 0.17; 95% CI, 0.10-0.30).

CONCLUSIONS

Maternal obesity is associated with an increased risk of a range of structural anomalies, although the absolute increase is likely to be small. Further studies are needed to confirm whether maternal overweight is also implicated.

5,10-Methylenetetrahydrofolate reductase gene variants and congenital anomalies: a HuGE review

The enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR) is involved in folate metabolism. The MTHFR gene is located on chromosome 1 (1p36.3), and two common alleles, the C677T (thermolabile) allele and the A1298C allele, have been described. The population frequency of C677T homozygosity ranges from 1% or less among Blacks from Africa and the United States to 20% or more among Italians and US Hispanics. C677T homozygosity in infants is associated with a moderately increased risk for spina bifida (pooled odds ratio = 1.8; 95% confidence interval: 1.4, 2.2). Maternal C677T homozygosity also appears to be a moderate risk factor (pooled odds ratio = 2.0; 95% confidence interval: 1.5, 2.8). The A 1298C allele combined with the C677T allele also could be associated with an increased risk for spina bifida. Some data suggest that the risk for spina bifida associated with C677T homozygosity may depend on nutritional status (e.g., blood folate levels, intake of vitamins) or on the genotype of other folate-related genes (e.g., cystathionine-beta-synthase and methionine synthase reductase). Studies of the C677T allele in relation to oral clefts, Down syndrome, and fetal anticonvulsant syndrome either have yielded conflicting results or have not been yet replicated.

The risk of major birth defects after intracytoplasmic sperm injection and in vitro fertilization

BACKGROUND

It is not known whether infants conceived with use of intracytoplasmic sperm injection or in vitro fertilization have a higher risk of birth defects than infants conceived naturally.

METHODS

We obtained data from three registries in Western Australia on births, births after assisted conception, and major birth defects in infants born between 1993 and 1997. We assessed the prevalence of major birth defects diagnosed by one year of age in infants conceived naturally or with use of intracytoplasmic sperm injection or in vitro fertilization.

RESULTS

Twenty-six of the 301 infants conceived with intracytoplasmic sperm injection (8.6 percent) and 75 of the 837 infants conceived with in vitro fertilization (9.0 percent) had a major birth defect diagnosed by one year of age, as compared with 168 of the 4000 naturally conceived infants (4.2 percent; P<0.001 for the comparison between either type of technology and natural conception). As compared with natural conception, the odds ratio for a major birth defect by one year of age, after adjustment for maternal age and parity, the sex of the infant, and correlation between siblings, was 2.0 (95 percent confidence interval, 1.3 to 3.2) with intracytoplasmic sperm injection, and 2.0 (95 percent confidence interval, 1.5 to 2.9) with in vitro fertilization. Infants conceived with use of assisted reproductive technology were more likely than naturally conceived infants to have multiple major defects and to have chromosomal and musculoskeletal defects.

CONCLUSIONS

Infants conceived with use of intracytoplasmic sperm injection or in vitro fertilization have twice as high a risk of a major birth defect as naturally conceived infants.

Reproductive technologies and the risk of birth defects

BACKGROUND

The extent to which birth defects after infertility treatment may be explained by underlying parental factors is uncertain.

METHODS

We linked a census of treatment with assisted reproductive technology in South Australia to a registry of births and terminations with a gestation period of at least 20 weeks or a birth weight of at least 400 g and registries of birth defects (including cerebral palsy and terminations for defects at any gestational period). We compared risks of birth defects (diagnosed before a child's fifth birthday) among pregnancies in women who received treatment with assisted reproductive technology, spontaneous pregnancies (i.e., without assisted conception) in women who had a previous birth with assisted conception, pregnancies in women with a record of infertility but no treatment with assisted reproductive technology, and pregnancies in women with no record of infertility.

RESULTS

Of the 308,974 births, 6163 resulted from assisted conception. The unadjusted odds ratio for any birth defect in pregnancies involving assisted conception (513 defects, 8.3%) as compared with pregnancies not involving assisted conception (17,546 defects, 5.8%) was 1.47 (95% confidence interval [CI], 1.33 to 1.62); the multivariate-adjusted odds ratio was 1.28 (95% CI, 1.16 to 1.41). The corresponding odds ratios with in vitro fertilization (IVF) (165 birth defects, 7.2%) were 1.26 (95% CI, 1.07 to 1.48) and 1.07 (95% CI, 0.90 to 1.26), and the odds ratios with intracytoplasmic sperm injection (ICSI) (139 defects, 9.9%) were 1.77 (95% CI, 1.47 to 2.12) and 1.57 (95% CI, 1.30 to 1.90). A history of infertility, either with or without assisted conception, was also significantly associated with birth defects.

CONCLUSIONS

The increased risk of birth defects associated with IVF was no longer significant after adjustment for parental factors. The risk of birth defects associated with ICSI remained increased after multivariate adjustment, although the possibility of residual confounding cannot be excluded. (Funded by the National Health and Medical Research Council and the Australian Research Council.).

Medication use during pregnancy, with particular focus on prescription drugs: 1976-2008

OBJECTIVE

The objective of the study was to provide information on overall medication use throughout pregnancy, with particular focus on the first trimester and specific prescription medications.

STUDY DESIGN

The study design included the Slone Epidemiology Center Birth Defects Study, 1976-2008, and the National Birth Defects Prevention Study, 1997-2003, which together interviewed more than 30,000 women about their antenatal medication use.

RESULTS

Over the last 3 decades, first-trimester use of prescription medication increased by more than 60%, and the use of 4 or more medications more than tripled. By 2008, approximately 50% of women reported taking at least 1 medication. Use of some specific medications markedly decreased or increased. Prescription medication use increased with maternal age and education, was highest for non-Hispanic whites, and varied by state.

CONCLUSION

These data reflect the widespread and growing use of medications by pregnant women and reinforce the need to study their respective fetal risks and safety.

National population-based estimates for major birth defects, 2010-2014

BACKGROUND

Using the National Birth Defects Prevention Network (NBDPN) annual data report, U.S. national prevalence estimates for major birth defects are developed based on birth cohort 2010-2014.

METHODS

Data from 39 U.S. population-based birth defects surveillance programs (16 active case-finding, 10 passive case-finding with case confirmation, and 13 passive without case confirmation) were used to calculate pooled prevalence estimates for major defects by case-finding approach. Fourteen active case-finding programs including at least live birth and stillbirth pregnancy outcomes monitoring approximately one million births annually were used to develop national prevalence estimates, adjusted for maternal race/ethnicity (for all conditions examined) and maternal age (trisomies and gastroschisis). These calculations used a similar methodology to the previous estimates to examine changes over time.

RESULTS

The adjusted national birth prevalence estimates per 10,000 live births ranged from 0.62 for interrupted aortic arch to 16.87 for clubfoot, and 19.93 for the 12 critical congenital heart defects combined. While the birth prevalence of most birth defects studied remained relatively stable over 15 years, an increasing prevalence was observed for gastroschisis and Down syndrome. Additionally, the prevalence for atrioventricular septal defect, tetralogy of Fallot, omphalocele, and trisomy 18 increased in this period compared to the previous periods. Active case-finding programs generally had higher prevalence rates for most defects examined, most notably for anencephaly, anophthalmia/microphthalmia, trisomy 13, and trisomy 18.

CONCLUSION

National estimates of birth defects prevalence provide data for monitoring trends and understanding the impact of these conditions. Increasing prevalence rates observed for selected conditions warrant further examination.

Infection and labor. V. Prevalence, microbiology, and clinical significance of intraamniotic infection in women with preterm labor and intact membranes

Amniotic fluid was retrieved by amniocentesis from 264 patients with preterm labor and intact membranes admitted to Yale-New Haven Hospital from Jan. 1, 1985, to July 31, 1988. The prevalence of a positive amniotic fluid culture was 9.1% (24/264). A total of 111 patients (42%) delivered preterm neonates, and 24 (21.6%) of those had positive amniotic fluid cultures. The diagnostic indexes of the Gram stain of amniotic fluid in the prediction of a positive amniotic fluid culture were as follows: sensitivity, 79.1%; specificity, 99.6%; positive predictive value, 95%; and negative predictive value, 98%. Endotoxin was detected with the limulus amebocyte lysate assay in 4.9% (13/264) of patients with preterm labor. All patients with endotoxin in the amniotic fluid delivered preterm neonates. The three most frequently isolated organisms were Ureaplasma urealyticum (n = 6), Fusobacterium species (n = 5), and Mycoplasma hominis (n = 4). Clinical chorioamnionitis was present in only 12.5% of the patients with positive amniotic fluid cultures. Women with positive amniotic fluid cultures had lower gestational ages and more advanced cervical dilatation on admission than women with negative cultures. Preterm infants born to mothers with positive amniotic fluid cultures had a higher incidence of respiratory distress syndrome and infectious complications than preterm neonates born after negative amniotic fluid cultures. These data underscore the frequency and importance of intraamniotic infections in women with preterm labor.

Diabetes mellitus and birth defects

OBJECTIVE

The purpose of this study was to examine associations between diabetes mellitus and 39 birth defects.

STUDY DESIGN

This was a multicenter case-control study of mothers of infants who were born with (n = 13,030) and without (n = 4895) birth defects in the National Birth Defects Prevention Study (1997-2003).

RESULTS

Pregestational diabetes mellitus (PGDM) was associated significantly with noncardiac defects (isolated, 7/23 defects; multiples, 13/23 defects) and cardiac defects (isolated, 11/16 defects; multiples, 8/16 defects). Adjusted odds ratios for PGDM and all isolated and multiple defects were 3.17 (95% CI, 2.20-4.99) and 8.62 (95% CI, 5.27-14.10), respectively. Gestational diabetes mellitus (GDM) was associated with fewer noncardiac defects (isolated, 3/23 defects; multiples, 3/23 defects) and cardiac defects (isolated, 3/16 defects; multiples, 2/16 defects). Odds ratios between GDM and all isolated and multiple defects were 1.42 (95% CI, 1.17-1.73) and 1.50 (95% CI, 1.13-2.00), respectively. These associations were limited generally to offspring of women with prepregnancy body mass index > or =25 kg/m(2).

CONCLUSION

PGDM was associated with a wide range of birth defects; GDM was associated with a limited group of birth defects.

Deliveries and children born after in-vitro fertilisation in Sweden 1982-95: a retrospective cohort study

BACKGROUND

In-vitro fertilisation is an effective treatment for infertility, but there is concern about the health of children. We investigated, in a retrospective registry study, malformations, cancers, and deaths in the complete Swedish in-vitro-fertilisation birth cohort compared with the general population.

METHODS

We collected data from all in-vitro-fertilisation clinics in Sweden and compared the obstetric outcomes of babies (n=5856) born between 1982 and 1995 with all babies born in the general population (n=1,505,724) during the same period, according to data from the Swedish Medical Birth Registry and the Registry of Congenital Malformations. We investigated the incidence of childhood cancer through the Swedish Cancer Registry. Data were stratified for maternal age, parity, previous subfertility, year of birth, and multiple of pregnancies.

FINDINGS

Multiple births occurred in 27% of pregnancies compared with 1% in the control group. In the in-vitro-fertilisation group, more babies were born preterm (<37 weeks) than controls (30.3 vs 6.3%) and more had low birthweights (<2500 g, 27.4 vs 4.6%). The perinatal mortality was 1.9% in the in-vitro fertilisation group and 1.1% in the controls. For in-vitro-fertilisation singletons, the risk ratios, adjusted for year of birth, for very preterm birth (<32 weeks) and very low birthweight (<1500 g) were 3.54 (95% CI 2.90-4.32) and 4.39 (3.62-5.32), respectively. Malformations occurred in 5.4% of all babies in the in-vitro-fertilisation group (1.39 [1.25-1.54]), and the rates of neural-tube defects and oesophageal atresia were higher than those in the controls. There was no increase in childhood cancer in the in-vitro-fertilisation group.

INTERPRETATION

A high frequency of multiple births and maternal characteristics were the main factors that led to adverse outcomes, and not the in-vitro-fertilisation technique itself. The clinical practice of in-vitro-fertilisation needs to be changed to lower the rate of multiple pregnancy.

The National Birth Defects Prevention Study

The National Birth Defects Prevention Study was designed to identify infants with major birth defects and evaluate genetic and environmental factors associated with the occurrence of birth defects. The ongoing case-control study covers an annual birth population of 482,000 and includes cases identified from birth defect surveillance registries in eight states. Infants used as controls are randomly selected from birth certificates or birth hospital records. Mothers of case and control infants are interviewed and parents are asked to collect buccal cells from themselves and their infants for DNA testing. Information gathered from the interviews and the DNA specimens will be used to study independent genetic and environmental factors and gene-environment interactions for a broad range of birth defects. As of December 2000, 7,470 cases and 3,821 controls had been ascertained in the eight states. Interviews had been completed with 70% of the eligible case and control mothers, buccal cell collection had begun in all of the study sites, and researchers were developing analysis plans for the compiled data. This study is the largest and broadest collaborative effort ever conducted among the nation's leading birth defect researchers. The unprecedented statistical power that will result from this study will enable scientists to study the epidemiology of some rare birth defects for the first time. The compiled interview data and banked DNA of approximately 35 categories of birth defects will facilitate future research as new hypotheses and improved technologies emerge.

A comparison of glyburide and insulin in women with gestational diabetes mellitus

BACKGROUND

Women with gestational diabetes mellitus are rarely treated with a sulfonylurea drug, because of concern about teratogenicity and neonatal hypoglycemia. There is little information about the efficacy of these drugs in this group of women.

METHODS

We studied 404 women with singleton pregnancies and gestational diabetes that required treatment. The women were randomly assigned between 11 and 33 weeks of gestation to receive glyburide or insulin according to an intensified treatment protocol. The primary end point was achievement of the desired level of glycemic control. Secondary end points included maternal and neonatal complications.

RESULTS

The mean (+/-SD) pretreatment blood glucose concentration as measured at home for one week was 114+/-19 mg per deciliter (6.4+/-1.1 mmol per liter) in the glyburide group and 116+/-22 mg per deciliter (6.5+/-1.2 mmol per liter) in the insulin group (P=0.33). The mean concentrations during treatment were 105+/-16 mg per deciliter (5.9+/-0.9 mmol per liter) in the glyburide group and 105+/-18 mg per deciliter (5.9+/-1.0 mmol per liter) in the insulin group (P=0.99). Eight women in the glyburide group (4 percent) required insulin therapy. There were no significant differences between the glyburide and insulin groups in the percentage of infants who were large for gestational age (12 percent and 13 percent, respectively); who had macrosomia, defined as a birth weight of 4000 g or more (7 percent and 4 percent); who had lung complications (8 percent and 6 percent); who had hypoglycemia (9 percent and 6 percent); who were admitted to a neonatal intensive care unit (6 percent and 7 percent); or who had fetal anomalies (2 percent and 2 percent). The cord-serum insulin concentrations were similar in the two groups, and glyburide was not detected in the cord serum of any infant in the glyburide group.

CONCLUSIONS

In women with gestational diabetes, glyburide is a clinically effective alternative to insulin therapy.

Risk of complications of pregnancy in women with type 1 diabetes: nationwide prospective study in the Netherlands

OBJECTIVE

To investigate maternal, perinatal, and neonatal outcomes of pregnancies in women with type 1 diabetes in the Netherlands.

DESIGN

Nationwide prospective cohort study.

SETTING

All 118 hospitals in the Netherlands.

PARTICIPANTS

323 women with type 1 diabetes who became pregnant between 1 April 1999 and 1 April 2000.

MAIN OUTCOME MEASURES

Maternal, perinatal, and neonatal outcomes of pregnancy.

RESULTS

84% (n = 271) of the pregnancies were planned. Glycaemic control early in pregnancy was good in most women (HbA(1c) < or = 7.0% in 75% (n = 212) of the population), and folic acid supplementation was adequate in 70% (n = 226). 314 pregnancies that went beyond 24 weeks' gestation resulted in 324 infants. The rates of pre-eclampsia (40; 12.7%), preterm delivery (101; 32.2%), caesarean section (139; 44.3%), maternal mortality (2; 0.6%), congenital malformations (29; 8.8%), perinatal mortality (9; 2.8%), and macrosomia (146; 45.1%) were considerably higher than in the general population. Neonatal morbidity (one or more complications) was extremely high (260; 80.2%). The incidence of major congenital malformations was significantly lower in planned pregnancies than in unplanned pregnancies (4.2% (n = 11) v 12.2% (n = 6); relative risk 0.34, 95% confidence interval 0.13 to 0.88).

CONCLUSION

Despite a high frequency of planned pregnancies, resulting in overall good glycaemic control (early) in pregnancy and a high rate of adequate use of folic acid, maternal and perinatal complications were still increased in women with type 1 diabetes. Neonatal morbidity, especially hypoglycaemia, was also extremely high. Near optimal maternal glycaemic control (HbA1c < or = 7.0%) apparently is not good enough.

Birth Defects Among Fetuses and Infants of US Women With Evidence of Possible Zika Virus Infection During Pregnancy

IMPORTANCE

Understanding the risk of birth defects associated with Zika virus infection during pregnancy may help guide communication, prevention, and planning efforts. In the absence of Zika virus, microcephaly occurs in approximately 7 per 10 000 live births.

OBJECTIVE

To estimate the preliminary proportion of fetuses or infants with birth defects after maternal Zika virus infection by trimester of infection and maternal symptoms.

DESIGN, SETTING, AND PARTICIPANTS

Completed pregnancies with maternal, fetal, or infant laboratory evidence of possible recent Zika virus infection and outcomes reported in the continental United States and Hawaii from January 15 to September 22, 2016, in the US Zika Pregnancy Registry, a collaboration between the CDC and state and local health departments.

EXPOSURES

Laboratory evidence of possible recent Zika virus infection in a maternal, placental, fetal, or infant sample.

MAIN OUTCOMES AND MEASURES

Birth defects potentially Zika associated: brain abnormalities with or without microcephaly, neural tube defects and other early brain malformations, eye abnormalities, and other central nervous system consequences.

RESULTS

Among 442 completed pregnancies in women (median age, 28 years; range, 15-50 years) with laboratory evidence of possible recent Zika virus infection, birth defects potentially related to Zika virus were identified in 26 (6%; 95% CI, 4%-8%) fetuses or infants. There were 21 infants with birth defects among 395 live births and 5 fetuses with birth defects among 47 pregnancy losses. Birth defects were reported for 16 of 271 (6%; 95% CI, 4%-9%) pregnant asymptomatic women and 10 of 167 (6%; 95% CI, 3%-11%) symptomatic pregnant women. Of the 26 affected fetuses or infants, 4 had microcephaly and no reported neuroimaging, 14 had microcephaly and brain abnormalities, and 4 had brain abnormalities without microcephaly; reported brain abnormalities included intracranial calcifications, corpus callosum abnormalities, abnormal cortical formation, cerebral atrophy, ventriculomegaly, hydrocephaly, and cerebellar abnormalities. Infants with microcephaly (18/442) represent 4% of completed pregnancies. Birth defects were reported in 9 of 85 (11%; 95% CI, 6%-19%) completed pregnancies with maternal symptoms or exposure exclusively in the first trimester (or first trimester and periconceptional period), with no reports of birth defects among fetuses or infants with prenatal exposure to Zika virus infection only in the second or third trimesters.

CONCLUSIONS AND RELEVANCE

Among pregnant women in the United States with completed pregnancies and laboratory evidence of possible recent Zika infection, 6% of fetuses or infants had evidence of Zika-associated birth defects, primarily brain abnormalities and microcephaly, whereas among women with first-trimester Zika infection, 11% of fetuses or infants had evidence of Zika-associated birth defects. These findings support the importance of screening pregnant women for Zika virus exposure.

Prenatal exome sequencing analysis in fetal structural anomalies detected by ultrasonography (PAGE): a cohort study

BACKGROUND

Fetal structural anomalies, which are detected by ultrasonography, have a range of genetic causes, including chromosomal aneuploidy, copy number variations (CNVs; which are detectable by chromosomal microarrays), and pathogenic sequence variants in developmental genes. Testing for aneuploidy and CNVs is routine during the investigation of fetal structural anomalies, but there is little information on the clinical usefulness of genome-wide next-generation sequencing in the prenatal setting. We therefore aimed to evaluate the proportion of fetuses with structural abnormalities that had identifiable variants in genes associated with developmental disorders when assessed with whole-exome sequencing (WES).

METHODS

In this prospective cohort study, two groups in Birmingham and London recruited patients from 34 fetal medicine units in England and Scotland. We used whole-exome sequencing (WES) to evaluate the presence of genetic variants in developmental disorder genes (diagnostic genetic variants) in a cohort of fetuses with structural anomalies and samples from their parents, after exclusion of aneuploidy and large CNVs. Women were eligible for inclusion if they were undergoing invasive testing for identified nuchal translucency or structural anomalies in their fetus, as detected by ultrasound after 11 weeks of gestation. The partners of these women also had to consent to participate. Sequencing results were interpreted with a targeted virtual gene panel for developmental disorders that comprised 1628 genes. Genetic results related to fetal structural anomaly phenotypes were then validated and reported postnatally. The primary endpoint, which was assessed in all fetuses, was the detection of diagnostic genetic variants considered to have caused the fetal developmental anomaly.

FINDINGS

The cohort was recruited between Oct 22, 2014, and June 29, 2017, and clinical data were collected until March 31, 2018. After exclusion of fetuses with aneuploidy and CNVs, 610 fetuses with structural anomalies and 1202 matched parental samples (analysed as 596 fetus-parental trios, including two sets of twins, and 14 fetus-parent dyads) were analysed by WES. After bioinformatic filtering and prioritisation according to allele frequency and effect on protein and inheritance pattern, 321 genetic variants (representing 255 potential diagnoses) were selected as potentially pathogenic genetic variants (diagnostic genetic variants), and these variants were reviewed by a multidisciplinary clinical review panel. A diagnostic genetic variant was identified in 52 (8·5%; 95% CI 6·4-11·0) of 610 fetuses assessed and an additional 24 (3·9%) fetuses had a variant of uncertain significance that had potential clinical usefulness. Detection of diagnostic genetic variants enabled us to distinguish between syndromic and non-syndromic fetal anomalies (eg, congenital heart disease only vs a syndrome with congenital heart disease and learning disability). Diagnostic genetic variants were present in 22 (15·4%) of 143 fetuses with multisystem anomalies (ie, more than one fetal structural anomaly), nine (11·1%) of 81 fetuses with cardiac anomalies, and ten (15·4%) of 65 fetuses with skeletal anomalies; these phenotypes were most commonly associated with diagnostic variants. However, diagnostic genetic variants were least common in fetuses with isolated increased nuchal translucency (≥4·0 mm) in the first trimester (in three [3·2%] of 93 fetuses).

INTERPRETATION

WES facilitates genetic diagnosis of fetal structural anomalies, which enables more accurate predictions of fetal prognosis and risk of recurrence in future pregnancies. However, the overall detection of diagnostic genetic variants in a prospectively ascertained cohort with a broad range of fetal structural anomalies is lower than that suggested by previous smaller-scale studies of fewer phenotypes. WES improved the identification of genetic disorders in fetuses with structural abnormalities; however, before clinical implementation, careful consideration should be given to case selection to maximise clinical usefulness.

FUNDING

UK Department of Health and Social Care and The Wellcome Trust.

Assisted reproductive technologies and the risk of birth defects—a systematic review

BACKGROUND

The risk of birth defects in infants born following assisted reproductive technology (ART) treatment is a controversial question. Most publications examining the prevalence of birth defects in ICSI and IVF infants compared to spontaneously conceived infants have serious methodological limitations; despite this, most researchers have concluded that there is no increased risk.

METHODS

We carried out a systematic review to identify all papers published by March 2003 with data relating to the prevalence of birth defects in infants conceived following IVF and/or ICSI compared with spontaneously conceived infants. Independent expert reviewers used criteria defined a priori to determine whether studies were suitable for inclusion in a meta-analysis. Fixed effects meta-analysis was performed for all studies and reviewer-selected studies.

RESULTS

Twenty-five studies were identified for review. Two-thirds of these showed a 25% or greater increased risk of birth defects in ART infants. The results of meta-analyses of the seven reviewer-selected studies and of all 25 studies suggest a statistically significant 30-40% increased risk of birth defects associated with ART.

CONCLUSIONS

Pooled results from all suitable published studies suggest that children born following ART are at increased risk of birth defects compared with spontaneous conceptions. This information should be made available to couples seeking ART treatment.

The prevalence of congenital anomalies in Europe

EUROCAT (European Surveillance of Congenital Anomalies) is the network of population-based registers of congenital anomaly in Europe, with a common protocol and data quality review, covering 1.5 million annual births in 22 countries. EUROCAT recorded a total prevalence of major congenital anomalies of 23.9 per 1,000 births for 2003-2007. 80% were livebirths. 2.5% of livebirths with congenital anomaly died in the first week of life. 2.0% were stillbirths or fetal deaths from 20 weeks gestation. 17.6% of all cases were terminations of pregnancy following prenatal diagnosis (TOPFA). Thus, congenital anomalies overwhelmingly concern children surviving the early neonatal period, who have important medical, social or educational needs. The prevalence of chromosomal anomalies was 3.6 per 1,000 births, contributing 28% of stillbirths/fetal deaths from 20 weeks gestation with congenital anomaly, and 48% of all TOPFA. Congenital heart defects (CHD) were the most common non-chromosomal subgroup, at 6.5 per 1,000 births, followed by limb defects (3.8 per 1,000), anomalies of urinary system (3.1 per 1,000) and nervous system defects (2.3 per 1,000). In 2004, perinatal mortality associated with congenital anomaly was 0.93 per 1,000 births, and TOPFA 4.4 per 1,000 births, with considerable country variation. Primary prevention of congenital anomalies in the population based on controlling environmental risk factors is a crucial policy priority, including preconceptional care and whole population approaches.

Overt and subclinical hypothyroidism complicating pregnancy

We studied the evolution of 150 pregnancies corresponding to 114 women (16-39 years old) with primary hypothyroidism. Fifty-one pregnancies (34%) were conceived under hypothyroidism: 16 overt (X +/- standard deviation [SD], thyroxine [T4]: 2.44 +/- 0.7 microg/dL; thyrotropin [TSH]: 33.4 +/- 8.82 mIU/L), and 35 subclinical hypothyroidism (T4: 6.93 +/- 1.88 microg/dL; TSH: 12.87 +/- 8.43 mIU/L); 99 pregnancies were conceived under euthyroidism while undergoing thyroid therapy. When treatment with levothyroxine was inadequate, the outcome of pregnancy was abortion in 60% of overtly hypothyroid patients and in 71.4% of subclinically hypothyroid patients, premature delivery in 20% and 7.2% respectively, and term delivery in 20% and 21.4%, respectively. When treatment was adequate, 100% of overtly hypothyroid patients and 90.5% of subclinically hypothyroid patients carried pregnancies to term; there were no abortions in any of the groups. Abortions, premature and term deliveries in patients who were euthyroid on levothyroxine at the time of conception were 4%, 11.1% and 84.9% respectively. Of the patients receiving levothyroxine therapy before conception, 69.5% had to increase the dose (mean increase 46.2 +/- 29.6 microg/d). Of 126 evaluated newborns, 110 were delivered at term while 16 were premature. Eight newborns, 4 were premature, had congenital malformations (6.3%), and 4 died. Our results show that the evolution of pregnancies did not depend on whether the hypothyroidism was overt or subclinical but mainly on the treatment received. The adequate treatment of hypothyroidism during gestation minimizes risks and generally, makes it possible for pregnancies to be carried to term without complications.

The teratogenicity of anticonvulsant drugs

BACKGROUND

The frequency of major malformations, growth retardation, and hypoplasia of the midface and fingers, known as the anticonvulsant embryopathy, is increased in infants exposed to anticonvulsant drugs in utero. However, whether the abnormalities are caused by the maternal epilepsy itself or by exposure to anticonvulsant drugs is not known.

METHODS

We screened 128,049 pregnant women at delivery to identify three groups of infants: those exposed to anticonvulsant drugs, those unexposed to anticonvulsant drugs but with a maternal history of seizures, and those unexposed to anticonvulsant drugs with no maternal history of seizures (control group). The infants were examined systematically for the presence of major malformations, signs of hypoplasia of the midface and fingers, microcephaly, and small body size.

RESULTS

The combined frequency of anticonvulsant embryopathy was higher in 223 infants exposed to one anticonvulsant drug than in 508 control infants (20.6 percent vs. 8.5 percent; odds ratio, 2.8; 95 percent confidence interval, 1.1 to 9.7). The frequency was also higher in 93 infants exposed to two or more anticonvulsant drugs than in the controls (28.0 percent vs. 8.5 percent; odds ratio, 4.2; 95 percent confidence interval, 1.1 to 5.1). The 98 infants whose mothers had a history of epilepsy but took no anticonvulsant drugs during the pregnancy did not have a higher frequency of those abnormalities than the control infants.

CONCLUSIONS

A distinctive pattern of physical abnormalities in infants of mothers with epilepsy is associated with the use of anticonvulsant drugs during pregnancy, rather than with epilepsy itself.

Outcomes of pregnancy in insulin dependent diabetic women: results of a five year population cohort study

OBJECTIVE

To monitor pregnancies in women with pre-existent insulin dependent diabetes for pregnancy loss, congenital malformations, and fetal growth in a geographically defined area of north west England.

DESIGN

Population cohort study.

SETTING

10 maternity units in Cheshire, Lancashire, and Merseyside which had no regional guidelines for the management of pregnancy in diabetic women.

SUBJECTS

462 pregnancies in 355 women with insulin dependent diabetes from the 10 centres over five years (1990-4 inclusive).

MAIN OUTCOME MEASURES

Numbers and rates of miscarriages, stillbirths, and neonatal and postneonatal deaths; prevalence of congenital malformations; birth weight in relation to gestational age.

RESULTS

Among 462 pregnancies, 351 (76%) resulted in a liveborn infant, 78 (17%) aborted spontaneously, nine (2%) resulted in stillbirth, and 24 (5%) were terminated. Of the terminations, nine were for congenital malformation. The stillbirth rate was 25.0/1000 total births (95% confidence interval 8.9 to 41.1) compared with a population rate of 5.0/1000, and infant mortality was 19.9/1000 live births (5.3 to 34.6) compared with 6.8/1000. The prevalence of congenital malformations was 94.0/1000 live births (63.5 to 124.5) compared with 9.7/1000 in the general population. When corrected for gestational age, mean birth weight in the sample was 1.3 standard deviations greater than that of infants of non-diabetic mothers. Infants with congenital malformations weighed less than those without.

CONCLUSION

In an unselected population the infants of women with pre-existent insulin dependent diabetes mellitus have a 10-fold greater risk of a congenital malformation and a fivefold greater risk of being stillborn than infants in the general population. Further improvements in the management of pregnancy in diabetic women are needed if target of the St Vincent declaration of 1989 is to be met.

Prevention of congenital malformations in infants of insulin-dependent diabetic mothers

From April 1977 to April 1981, 420 deliveries of infants of insulin-dependent diabetic women were performed in our department. Of the infants delivered, 23 had congenital malformations (5.5%). The malformation rate was 1.4% for infants of 420 nondiabetic women. Strict metabolic control was begun after 8 wk gestation in 292 of the diabetic women who delivered 22 infants with congenital malformations (7.5%). Intensive treatment was begun before conception in 128 diabetic women planning pregnancy. There was only one malformation in infants of this group (0.8%), a significant reduction from the anomaly rate in the late registrants (X2 = 7.84; P less than 0.01). These observations indicate that reasonable metabolic control started before conception and continued during the first weeks of pregnancy can prevent malformations in infants of diabetic mothers.

Consequences of varicella and herpes zoster in pregnancy: prospective study of 1739 cases

In a joint prospective study in Germany and the United Kingdom between 1980 and 1993, 1373 women who had varicella and 366 who had herpes zoster during the first 36 weeks of gestation were followed up. 9 cases of congenital varicella syndrome were identified, all occurring after maternal varicella during the first 20 weeks of gestation. The highest risk (2.0%) was observed between 13-20 weeks gestation, with 7 affected infants identified among 351 pregnancies (95% CI of risk 0.8-4.1%). Only 2 cases of congenital varicella syndrome were identified among 472 pregnancies in which maternal varicella occurred before 13 weeks (observed risk 0.4%, 95% CI 0.05-1.5%). Herpes zoster in infancy was reported in 10 children whose mothers had had varicella in pregnancy. No infants with clinical evidence of intrauterine infection were born to the 366 women with herpes zoster in pregnancy (upper 95% confidence limit of estimated risk 1.0%). Varicella-zoster-specific IgM antibody was found at birth in 4 of 16 (25%) infants with clinical manifestations of intrauterine infection and persistent specific IgG antibody in 5 of 7 infants tested. The corresponding rates in asymptomatic infants whose mothers had varicella were 12% (76/615) and 7% (22/335) respectively. No serological evidence of intrauterine infection was found in infants who mothers had herpes zoster in pregnancy. In 97 pregnant women, varicella occurred after post-exposure prophylaxis with anti-varicella-zoster immunoglobulin. No cases of congenital varicella syndrome or zoster in infancy occurred in this group. Our estimates provide a sound basis for counselling women with varicella in pregnancy. Although the risk of congenital varicella syndrome is small, the outcome for the affected infant is so serious that a reliable method of prenatal diagnosis would be valuable. In the long term, prevention of maternal varicella would be an option if a safe and effective vaccine were to become routinely available.

Abnormalities of gyration, heterotopias, tuberous sclerosis, focal cortical dysplasia, microdysgenesis, dysembryoplastic neuroepithelial tumour and dysgenesis of the archicortex in epilepsy. Clinical, EEG and neuroimaging features in 100 adult patients

Cerebral cortical dysgenesis (CD) is a heterogeneous disorder of cortical development and organization commonly associated with epilepsy, with a variety of subtypes. We reviewed the clinical, EEG and neuroimaging features in 100 adult patients with CD. There were 39 men and 61 women with a median age of 27 years (range 15-63 years). All patients were referred because of medically refractory epilepsy. Median age at seizure onset was 10 years (range 3 weeks to 39 years); in 30 patients, onset was in adulthood. The epilepsy was classified as generalized in 16 patients and localization-related in 84. Of the latter, the epileptic syndromes in decreasing frequency were frontal (32%), temporal (31%), parietal (14%) and occipital (7%). Only 15% of patients had a history of status epilepticus. Prenatal/perinatal problems were reported in 32 patients but these were severe in only four: exposure to drugs (three) and infection (one) during the first trimester. Delayed developmental milestones were seen in 10%, mental retardation in 9%, additional congenital abnormalities in 4% and neurological deficits in 14% of patients. Diagnosis of CD was based on neuroimaging in 70, pathology in four and both methods in the remaining 26. The following subcategories were identified: agyria/diffuse macrogyria (four patients), focal macrogyria (16), focal polymicrogyria (one), focal macrogyria/polymicrogyria associated with a cleft (11), minor gyral abnormalities (seven), subependymal grey matter heterotopia (20), bilateral subcortical laminar grey matter heterotopia (eight), tuberous sclerosis (five), focal cortical dysplasia/microdysgenesis (seven) and dysembryoplastic neuroepithelial tumours (DNT) (21). Sixty-eight percent of patients had normal CT and 19 out of 36 patients had normal previous conventional MRI. MRI-based hippocampal volume measurements in 47 patients revealed ratios (smaller: larger hippocampus) of < 0.90 in 16, 0.90-0.94 in 14 and > or = 0.95 in 17 patients. EEGs were normal in only five patients. Alpha rhythm was preserved in 78 patients, including one patient with bilateral posterior macrogyria. Localized polymorphic slow activity was present in 43 patients. Five of 68 patients with focal/unilateral CD had only bilateral independent/synchronous spiking and 14 out of 32 with diffuse/bilateral CD only focal/unilateral spiking. In 60 patients with nondiffuse CD or with abnormal gyration or DNT, the epileptiform abnormalities were less extensive than coextensive with the lesion in 28, more extensive than and overlapped the lesion in 18 and remote from the lesion in five; nine patients did not have epileptiform abnormalities. There was poor correlation between the epileptic syndromes and EEG abnormalities and the location/extent of CD as defined by MRI and pathology.(ABSTRACT TRUNCATED AT 400 WORDS)

Prepregnancy Obesity as a Risk Factor for Structural Birth Defects

OBJECTIVE

To describe the relation between maternal obesity, overweight and underweight status, and 16 categories of structural birth defects.

DESIGN

An ongoing multisite, case-control study. Clinical geneticists reviewed all of the cases, excluding those that had or were strongly suspected to have a single-gene disorder or chromosomal abnormality. Mothers with preexisting diabetes were also excluded. Body mass index was based on maternal report of height and weight prior to pregnancy.

SETTING

Eight participating states in the United States.

PARTICIPANTS

Mothers enrolled in the National Birth Defects Prevention Study who had index pregnancies between October 1, 1997, and December 31, 2002.

MAIN EXPOSURE

Maternal obesity.

MAIN OUTCOME MEASURES

Crude and adjusted odds ratios.

RESULTS

Mothers of offspring with spina bifida, heart defects, anorectal atresia, hypospadias, limb reduction defects, diaphragmatic hernia, and omphalocele were significantly more likely to be obese than mothers of controls, with odds ratios ranging between 1.33 and 2.10. Mothers of offspring with gastroschisis were significantly less likely to be obese than mothers of controls.

CONCLUSIONS

To our knowledge, this is the first population-based study of its scale to examine prepregnancy obesity and a range of structural birth defects. These results suggest a weak to moderate positive association of maternal obesity with 7 of 16 categories of birth defects and a strong inverse association with gastroschisis. The mechanisms underlying these associations are not yet understood but may be related to undiagnosed diabetes.