Original article: is the protective association between hyperemesis gravidarum and birth defects biased by pregnancy termination?

Hyperemesis gravidarum and the risk of offspring morbidity: a longitudinal cohort study

PURPOSE

Hyperemesis gravidarum has the potential to affect the long-term health of offspring. We examined whether maternal hyperemesis gravidarum was associated with the risk of hospitalization for childhood morbidity.

METHODS

We conducted a longitudinal cohort study of 1,189,000 children born in Quebec, Canada, between April 2006 and March 2021. The main exposure measure was maternal hyperemesis gravidarum requiring hospitalization in the first or second trimester. The outcome was any pediatric admission between birth and 16 years of age, with follow-up ending in March 2022. We used Cox regression models adjusted for maternal and socioeconomic factors to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association between maternal hyperemesis gravidarum and childhood hospitalization.

RESULTS

Among 1,189,000 children, 6904 (0.6%) were exposed to maternal hyperemesis gravidarum. Hospitalization rates at age 16 years were higher for children exposed to hyperemesis gravidarum than unexposed children (47.6 vs 43.9 per 100 children). Relative to no exposure, hyperemesis gravidarum was associated with a 1.21 times greater risk of any hospitalization before 16 years (95% CI 1.17-1.26). Hyperemesis gravidarum was associated with hospitalization for neurologic (HR 1.50, 95% CI 1.32-1.71), developmental (HR 1.51, 95% CI 1.29-1.76), digestive (HR 1.40, 95% CI 1.30-1.52), and allergic disorders (HR 1.39, 95% CI 1.24-1.56). When contrasted with preeclampsia, hyperemesis gravidarum was a stronger risk factor for these outcomes.

CONCLUSIONS

Maternal hyperemesis gravidarum is associated with an increased risk of childhood hospitalization, especially for neurologic, developmental, digestive, and atopic disorders.

WHAT IS KNOWN

• Hyperemesis gravidarum is associated with neurodevelopmental disorders in offspring. • However, the effect of hyperemesis gravidarum on other childhood morbidity is unclear.

WHAT IS NEW

• In this longitudinal cohort study of 1.2 million children, maternal hyperemesis gravidarum was associated with a greater risk of hospitalization before age 16 years. • Exposure to hyperemesis gravidarum was associated with developmental, neurologic, atopic, and digestive morbidity in childhood.

Perinatal outcomes of infants born to mothers with hyperemesis gravidarum: A systematic review and meta-analysis

BACKGROUND

Hyperemesis gravidarum is the severe form of nausea and vomiting during pregnancy and can lead to undernutrition and low maternal weight gain. Previous epidemiologic and animal studies have shown that undernutrition and low maternal weight gain in pregnancy can increase the risk of unfavorable perinatal outcomes, like shorter gestational age, small for gestational age and lower weight at birth.

OBJECTIVE

To evaluate the effect of hyperemesis gravidarum on perinatal outcomes.

SEARCH STRATEGY

OVID Medline and Embase were searched from inception to February 9th, 2022.

STUDY ELIGIBILITY

Studies reporting on perinatal outcomes of infants born to mothers with hyperemesis gravidarum or severe nausea and vomiting in pregnancy were included. Case reports, case series, animal studies, reviews, editorials and conference abstracts were excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected and extracted data. Risk of bias was assessed by the Newcastle-Ottawa Quality Assessment Scale. We conducted meta-analyses where possible.

RESULTS

Our search yielded 1387 unique papers, of which 61 studies (n = 20,532,671 participants) were included in our systematic review. Meta-analyses showed that hyperemesis gravidarum was associated with preterm birth < 34 weeks (2 studies n = 2,882: OR 2.81, 95 %CI: 1.69-4.67), birth weight < 1500 g (2 studies, n = 489,141: OR 1.43, 95 %CI: 1.02-1.99), neonatal resuscitation (2 studies, n = 4,289,344: OR 1.07, 95 %CI: 1.05-1.10), neonatal intensive care unit admission (7 studies, n = 6,509,702: OR 1.20, 95 %CI: 1.14-1.26) and placental abruption (6 studies, n = 9,368,360: OR 1.15, 95 %CI: 1.05-1.25). Hyperemesis gravidarum was associated with reductions in birthweight > 4000 g (2 studies, n = 5,503,120: OR 0.74, 95 %CI: 0.72-0.76) and stillbirth (9 studies, n = 3,973,154: OR 0.92, 95 %CI: 0.85-0.99). Meta-analyses revealed no association between hyperemesis gravidarum and Apgar scores < 7 at 1 and 5 min; fetal loss, perinatal deaths and neonatal deaths.

CONCLUSION

Hyperemesis gravidarum is associated with several adverse perinatal outcomes including low birth weight and preterm birth. We also found that pregnancies complicated by hyperemesis gravidarum less frequently were complicated by macrosomia and stillbirth. We were unable to investigate underlying mechanisms.

Association of Birth Defects With Child Mortality Before Age 14 Years

IMPORTANCE

Causes of death in children with birth defects are poorly understood.

OBJECTIVE

To determine mortality rates by cause of death in children with and without birth defects.

DESIGN, SETTING, AND PARTICIPANTS

This longitudinal cohort study included a population-based sample of 1 037 688 children and was conducted in all hospitals in Quebec, Canada, with 7 700 596 person-years of follow-up between birth and age 14 years (April 1, 2006, to March 31, 2020).

EXPOSURES

Presence or absence of a birth defect.

MAIN OUTCOMES AND MEASURES

Outcomes were all-cause and cause-specific mortality. Hazard ratios (HRs) and 95% CIs were computed for the association between birth defects and mortality with Cox proportional hazards models adjusted for patient characteristics.

RESULTS

Among the 1 037 688 children in the cohort, 95 566 had birth defects (56.5% boys). There were 532 542 boys in the cohort (51.3%), and mean (SD) age at the end of follow-up was 7.42 (3.72) years. There were 918 deaths among children with defects, and the mean (SD) age was 0.93 (2.07) years at death; there were 1082 deaths among the 942 122 children without defects, and the mean (SD) age at death was 0.50 (1.51) years. Mortality rates were higher for children with birth defects compared with no defect (1.3 vs 0.2 deaths per 1000 person-years, respectively). Girls (HR, 5.66; 95% CI, 4.96-6.47) and boys (HR, 4.69; 95% CI, 4.15-5.29) with birth defects had an elevated risk of death before 14 years compared with unaffected children. Birth defects were associated with mortality from circulatory (HR, 26.59; 95% CI, 17.73-39.87), respiratory (HR, 23.03; 95% CI, 15.09-35.14), and digestive causes (HR, 31.77; 95% CI, 11.87-85.04), but anomalies were rarely listed as the cause of death. Compared with children with no defect, those with birth defects were at greatest risk of death between 28 and 364 days of life.

CONCLUSIONS AND RELEVANCE

This cohort study of 1 037 688 children suggests that birth defects were strongly associated with mortality owing to circulatory, respiratory, and digestive causes. This finding suggests that the contribution of birth defects may be underestimated in mortality statistics.