Changes in e-cigarette and cigarette use during pregnancy and their association with small-for-gestational-age birth.

BACKGROUND: Despite increased e-cigarette use, limited research has focused on changes in e-cigarette and combustible cigarette use around pregnancy and the subsequent effects on infant health. OBJECTIVE: This study aimed to characterize changes in e-cigarette and cigarette use from before to during pregnancy and examine their associations with small-for-gestational-age birth. STUDY DESIGN: This was a secondary data analysis of 2016-2018 data of the US Pregnancy Risk Assessment Monitoring System. We analyzed women aged ≥18 years who had a recent live birth (unweighted: n=105,438; weighted: n=5,446,900). Women were grouped on the basis of their self-reported e-cigarette and/or cigarette use 3 months before pregnancy (exclusive e-cigarette users, exclusive cigarette smokers, dual users, and nonusers) and change in e-cigarette and cigarette use during pregnancy (continuing use, quitting, switching, and initiating use). Small-for-gestational-age was defined as a birthweight below the 10th percentile for infants of the same sex and gestational age. We described the distributions of women's sociodemographic and pregnancy characteristics in both weighted and unweighted samples. We used multivariable log-binomial regression models to estimate the relative risks for the associations between changes in e-cigarette and cigarette use during pregnancy and risk of small-for-gestational-age, adjusting for significant covariates. RESULTS: The rates of cessation during pregnancy were the highest among exclusive e-cigarette users (weighted percentage, 80.7% [49,378/61,173]), followed by exclusive cigarette users (54.4% [421,094/773,586]) and dual users (46.4% [69,136/149,152]). Among exclusive e-cigarette users, continued users of e-cigarettes during pregnancy had a higher risk of small-for-gestational-age than nonusers (16.5% [1849/11,206]) vs 8.8% [384,338/4,371,664]; confounder-adjusted relative risk, 1.52 [95% confidence interval, 1.45-1.60]), whereas quitters of e-cigarettes had a similar risk of small-for-gestational-age with nonusers (7.7% [3730/48,587] vs 8.8% [384,338/4,371,664]; relative risk, 0.84 [95% confidence interval, 0.82-0.87]). Among exclusive cigarette users, those who completely switched to e-cigarettes during pregnancy also had a similar risk of small-for-gestational-age with nonusers (7.6% [259/3412] vs 8.8% [384,338/4,371,664]; relative risk, 0.83 [95% confidence interval, 0.73-0.93]). Among dual users before pregnancy, the risk of small-for-gestational-age decreased from 23.2% (7240/31,208) (relative risk, 2.53 [95% confidence interval, 2.47-2.58]) if continuing use to 16.9% (6617/39,142) (relative risk, 1.88 [95% confidence interval, 1.83-1.92]) if only quitting e-cigarettes or 15.1% (1254/8289) (relative risk, 1.61 [95% confidence interval, 1.52-1.70]) if only quitting cigarettes and further to 11.2% (7589/67,880) (relative risk, 1.23 [95% confidence interval, 1.20-1.25]) if both quitting e-cigarettes and cigarettes during pregnancy, compared with nonusers. CONCLUSION: Among exclusive e-cigarette users, quitting e-cigarettes during pregnancy normalized the risk of small-for-gestational-age. Among exclusive cigarette users, quitting smoking or completely switching to e-cigarettes normalized small for gestational age risk. Among dual users, smoking cessation has a greater effect than quitting e-cigarettes only, although discontinuing the use of both may lead to the greatest reduction in the risk of small-for-gestational-age.

Parameterization of the mid-trimester drop in blood pressure trajectory during pregnancy and its utility for predicting preeclampsia.

OBJECTIVES: The purpose of this study was to parameterize mid-trimester drop in blood pressure (BP) trajectory during pregnancy and to evaluate its utility for predicting preeclampsia. METHODS: To develop parametric models for BP trajectory during pregnancy, we used data from 7923 Chinese pregnant women with 24 810 routine antenatal care visits. Then, we evaluated the utility of BP trajectory parameters for predicting clinician-diagnosed preeclampsia in a separate sample of 3524 pregnant women from a randomized controlled trial of prenatal vitamin supplementation conducted in the same area. We focused on parameters related to the mid-trimester BP drop, including the gestational age and BP value at the nadir (lowest point), change in BP, velocity, and area under curve during two periods (from 12 weeks of gestation to the nadir and from the nadir to 33 weeks of gestation). RESULTS: All participants in our analysis had a mid-pregnancy drop in their SBP, DBP, and mean arterial pressure (MAP) trajectories. There were high correlations (|r| > 0.90) among trajectory parameters of the same BP measure. The final prediction model included selective parameters of SBP, DBP, and MAP trajectories, prepregnancy BMI and gestational age at the first antenatal care visit. The area under the receiver-operating curve for predicting preeclampsia was 0.886 (95% confidence interval 0.846--0.926) in the training dataset and 0.802 (0.708--0.895) in the validation dataset. CONCLUSION: Our novel BP trajectory parameters are informative and can predict preeclampsia at a clinically acceptable level.

Reducing fetal origins of childhood obesity through maternal smoking cessation during pregnancy: an intervention study.

Rapid infant weight gain predicts childhood obesity. We aimed to estimate effect size and identify critical timing for intervention-assisted smoking cessation during pregnancy to impact infant weight gain. We followed 25 mother-infant dyads in the UB Pregnancy and Smoking Cessation Study (Buffalo, NY, USA). Maternal smoking status was biochemically verified and monitored through pregnancy. Birth weight and length were extracted from birth records. Research staff measured infant weight and length at 2 weeks and monthly from 1 to 12 months of age. Mixed models were used to fit infant BMI-for-age z-score (ZBMI) trajectories. We found infants of quitters had lower ZBMI gain from birth to 12 months (mean ± SD, 1.13 ± 1.16) than infants of persistent smokers (2.34 ± 1.40; p = 0.035), with Cohen's d effect size being large (0.96). The infant ZBMI gain from birth to 12 months was low (<0.47) if smoking cessation was initiated between 15 and 27 weeks of pregnancy, but started to increase if quitting at 28 weeks (0.65) and accelerated with time (e.g., 3.16 if quitting at 36 weeks). We concluded maternal smoking cessation during pregnancy may reduce fetal origins of obesity through reducing infant weight gain, especially if quitting smoking by 27 weeks of pregnancy.