Hyperemesis gravidarum and birth outcomes—a population‐based cohort study of 2.2 million births in the Norwegian Birth Registry

Abstract

Objective To study associations between hyperemesis gravidarum (HG) and birth outcomes.Design Population-based cohort study.Setting Norway.Sample Singleton births in the Norwegian Birth Registry, 1967-2009 (n = 2 270 363).Methods Multiple logistic regression was applied to study associations between HG and dichotomous outcomes; multiple linear regression to study associations between HG, birthweight and gestational length. Generalised estimating equations were applied to obtain valid standard errors. Sub-analysis on data with available information on smoking was conducted (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)).Main outcome measures Small and large for gestational age (SGA/LGA), Apgar score after 5 minutes, very preterm and preterm birth (VPTB/PTB), perinatal death, stillbirth, neonatal death, birthweight and gestational length.Results No associations between HG and adverse pregnancy outcomes were observed in crude analyses, except for VPTB (odds ratio [OR] 0.79, 95% CI 0.67-0.93). In adjusted analysis, HG was associated with perinatal death (OR 1.27, 95% CI 1.08-1.48). Inverse associations were observed between HG and VPTB (OR 0.80, 95% CI 0.68-0.94) and LGA (OR 0.95, 95% CI 0.90-0.99). Sub-analyses showed no associations between HG and perinatal death (OR 1.29, 95% CI 0.91-1.83). The inverse associations between HG, VPTB and LGA were strengthened (OR 0.66, 95% CI, respectively). Exposed babies had reduced birthweight and gestational length compared with unexposed, adjusted difference À 21.4 g and À 0.5 days, respectively. Adjustment for smoking slightly strengthened the impact of HG on birthweight.Conclusions Inverse associations for HG and VPTB and LGA were observed. HG was associated with slight reductions in birthweight and gestational age.

Relationship between hyperemesis gravidarum and small-for-gestational-age in the Japanese population: the Japan Environment and Children’s Study (JECS)

“…The recent Norwegian Mother and Child Cohort Study reported that HG-exposed babies had slightly reduced birthweight, but there were no association between HG and SGA birth [18, 23], although it should be noted that no adjustment for weight gain was made, while adjusting for smoking status slightly increased the effect of HG. Further reports have suggested that HG does not influence birth weight [11, 16, 17].…”

“…Furthermore, severe maternal weight loss in early pregnancy, typically linked with extreme NVP, has been linked with growth restriction [9]. However, other reports have suggested that HG does not influence growth restriction [14, 15], birth weight [11, 16, 17], or risk for SGA [18]. Thus, there is as yet no clear consensus on this issue [11, 16, 17].…”

Hyperemesis gravidarum and long‐term mortality: a population‐based cohort study

“…Also, the influence of socio‐economic status on HG risk is inconsistent in the literature,33, 39, 40 but low socio‐economic status is associated with increased morbidity and mortality 41, 42, 43…”

Hyperemesis gravidarum and placental dysfunction disorders

“…Two large cohort studies in Scandinavian countries showed that hyperemesis was associated with higher risk of preeclampsia, lower birth weight and shorter gestational duration [15, 21]. This was supported by several studies suggesting higher risks of low birth weight (LBW), small for gestational age (SGA), and preterm birth if mothers experienced hyperemesis [22–24].…”