Nausea and vomiting of pregnancy beyond the first trimester and the risk of preterm birth

Abstract

Although most pregnant persons with nausea and vomiting of pregnancy (NVP) have symptoms that improve after the first trimester, approximately 20% experience NVP later in gestation. Little is known about pregnancy outcomes among these individuals. We aimed to investigate pregnancy outcomes among those with NVP after the first trimester. This is a secondary analysis of 9117 nulliparas from the NuMoM2b cohort who underwent NVP assessment with the Pregnancy-Unique Quantification of Emesis (PUQE) scale at three study visits; “V1” at 12.5±2.7 weeks, “V2” at 19.4±2.5 weeks, and “V3” at 28.0±3.2 weeks. Scores ranged 3-15 and were classified as having no NVP symptoms (PUQE score=3), mild (4-6) or moderate/severe (≥ 7) NVP at each visit. Chi-square analyses were used to compare the rate of adverse pregnancy outcomes (APO); small for gestational age, gestational hypertension, stillbirth, gestational diabetes, preterm birth (PTB) < 34 weeks, PTB < 37 weeks, across NVP categories at each study visit. Separate logistic regression models were used to estimate the association between degree of NVP at each visit and the odds of PTB < 37 weeks – adjusted for covariates (age, body mass index, race/ethnicity, smoking, gestational hypertension, depression). A separate sensitivity analysis was performed with additional adjustment for rate of gestational weight gain (GWG) per week. Degree of NVP at V1 and V3 was not associated with APO. There was a higher rate of PTB < 37 weeks in those with mild (10.1%) and moderate/severe NVP (13.3% ) versus having no NVP (8.2%) in V2 (χ2=13.8, p=0.001) (Table 1). On adjusted analysis, there was a marginally higher odds of PTB < 37 weeks among those with mild NVP at V2 (OR 1.21, 95% CI 1.00 to 1.47, p=0.050) and significantly higher odds with moderate/severe NVP at V2 (OR 1.60, 95% CI 1.09 to 2.36, p=0.017) versus having no NVP. This relationship was strengthened after adding GWG as a covariate (OR 1.85, 95% CI: 1.20 to 2.86, p=0.005). Moderate/severe NVP in mid-gestation may be associated with a higher risk of PTB.