Severity of nausea and vomiting in pregnancy and early childhood neurobehavioural outcomes: The Growing Up in Singapore Towards Healthy Outcomes study

Background: Nausea and vomiting of pregnancy (NVP) affects 50 to 80 per cent of women. The existing literature has examined NVP from the perspective of the mother, and relatively less is known about offspring outcomes.

Objectives: To study the relationships of NVP with social-emotional, behavioural, and cognitive outcomes of the offspring in a multi-ethnic Asian cohort.

Methods: In the Growing Up in Singapore Towards Healthy Outcomes prospective mother-offspring cohort study, mothers responded to a structured NVP questionnaire at 26-28 weeks' gestation (n = 1172) and participants with severe NVP were confirmed using medical records. Children underwent multiple neurodevelopmental assessments throughout childhood. We conducted multivariable regressions with post-estimation predictive margins to understand the associations of NVP with offspring neurobehavioural outcomes, which included 1-year Infant-Toddler Social and Emotional Assessment, 1.5-year Quantitative Checklist for Autism in Toddlers, 2-year Bayley Scales of Infant and Toddler Development, 2- and 4-year Child Behavior Checklist, and 4.5-year Kaufman Brief Intelligence Test. Analyses were adjusted for household income, birth variables, maternal mental health, and other relevant medical variables. Cohen's d effect sizes were calculated using standardised mean differences (μ_d ).

Results: Mothers were categorised into no (n = 296, 25.3%), mild-moderate (n = 686, 58.5%), and severe NVP (n = 190, 16.2%), of whom 67 (5.7%) required admission. Compared to children of mothers who had no or mild-moderate NVP, children with exposure to severe NVP exhibited more externalising behaviours (μ_d 2.0, 95% CI 0.3, 3.6; Cohen's d = 0.33) and social communication difficulties before 2 years (μ_d 4.1, 95% Cl 0.1, 8.0; Cohen's d = 0.38), both externalising (μ_d 1.5, 95% CI 0.4, 2.6; Cohen's d = 0.43) and internalising behaviours at 2 years (μ_d 1.2, 95% CI 0.1, 2.2; Cohen's d = 0.35), and only internalising behaviours after 2 years (μ_d 1.1, 95% CI 0.4, 2.0; Cohen's d = 0.37).

Conclusions: Severe NVP is highly prevalent in this Asian cohort and may be adversely associated with multiple offspring neurobehavioural outcomes.

Keywords: Nausea in pregnancy; behaviours; child development; hyperemesis gravidarum; vomiting in pregnancy.