Association between nausea and vomiting during pregnancy and adverse pregnancy outcomes: findings from the nuMoM2b study

Abstract

Purpose: Nausea and vomiting of pregnancy (NVP), including its severe form hyperemesis gravidarum (HG), have been linked to various perinatal outcomes, though findings remain inconsistent. This study aimed to examine the association between NVP severity and adverse pregnancy outcomes and to evaluate whether gestational weight gain (GWG) mediates these relationships. Methods: We analyzed data from 8396 nulliparous women enrolled in the U.S. nuMoM2b cohort. NVP severity was measured using the Pregnancy-Unique Quantification of Emesis (PUQE) score across three prenatal visits and categorized as none, one, and ≥2 visits of medium-to-severe NVP. Perinatal outcomes included birth weight, gestational age, preterm delivery, small for gestational age (SGA), and low birth weight (LBW). GWG adequacy was assessed per Institute of Medicine guidelines. Multivariable regression models were used, adjusting for sociodemographic and clinical covariates. Results: Overall, 81.6% of women reported no visit with medium-to-severe NVP, 16.2% with one such visit, and 2.3% with two or three such visits. One visit with medium-to-severe NVP was associated with a modest reduction in birth weight (−41.4 g; 95% CI: −72.6, −10.2). Inadequate GWG—regardless of NVP status—was consistently associated with shorter gestation (−0.53 weeks), lower birth weight (−261.3 g), and increased risks of preterm birth, LBW, and SGA (ORs 1.66–2.75). Conclusion: NVP severity alone showed limited impact on short-term pregnancy outcomes. However, inadequate GWG emerged as a key modifiable risk factor. These findings underscore the importance of nutritional support and symptom management during pregnancy, particularly for women with moderate-to-severe NVP. Long-term outcomes warrant further investigation.