Is soft drink consumption associated with gestational hypertension? Results from the BRISA cohort

It is still unknown whether excessive consumption of sugar-sweetened beverages may be linked to gestational hypertensive disorders, other than preeclampsia. This study investigated the association between soft drink consumption and hypertension during pregnancy, analyzing the relationship from the perspective of counterfactual causal theory. Data from pregnant women of the BRISA cohort were analyzed (1,380 in São Luis and 1,370 in Ribeirão Preto, Brazil). The explanatory variable was the frequency of soft drink consumption during pregnancy obtained in a prenatal interview. The outcome was gestational hypertension based on medical diagnosis, at the time of delivery. A theoretical model of the association between soft drink consumption and gestational hypertension was constructed using a directed acyclic graph. Marginal structural models (MSM) weighted by the inverse of the probability of soft drink consumption were also employed. Using Poisson regression analysis, high soft drink consumption (≥7 times/week) was associated with gestational hypertension in São Luís (RR=1.48; 95%CI: 1.03-2.10), in Ribeirão Preto (RR=1.51; 95%CI: 1.13-2.01), and in the two cohorts combined (RR=1.45; 95%CI: 1.16-1.82) compared to lower exposure (<7 times/week). In the MSM, the association between high soft drink consumption and gestational hypertension was observed in Ribeirão Preto (RR=1.63; 95%CI: 1.21-2.19) and in the two cohorts combined (RR=1.51; 95%CI: 1.15-1.97), but not in São Luís (RR=1.26; 95%CI: 0.79-2.00). High soft drink consumption seems to be a risk factor for gestational hypertension, suggesting that it should be discouraged during pregnancy.

Parental Obesity and Offspring Pubertal Development: Project Viva.

OBJECTIVE: To investigate the association of preconception parental obesity (body mass index [BMI] ≥30 kg/m2) with offspring pubertal development. STUDY DESIGN: Among 1377 children from a prospective prebirth cohort in Boston, we examined markers of puberty (age at peak height velocity [PHV], age at menarche, self-reported pubertal development score), and adrenarche (pictograph Tanner pubic hair staging). We used multivariable regression models to examine associations of maternal and paternal obesity with offspring pubertal indices, and applied marginal structural models to estimate the controlled direct effect not mediated by offspring prepubertal BMI. RESULTS: The prevalence of paternal obesity alone, maternal obesity alone, and biparental obesity were 10.5%, 10.1%, and 5%, respectively. After adjusting for demographic and socioeconomic factors, parental heights and maternal age at menarche, maternal obesity alone (vs neither parent with obesity) was associated with earlier age at PHV (ß -0.30 years; 95% CI -0.57, -0.03) and higher early adolescent pubertal score (0.29 units; 0.10, 0.48) in boys, but not with pubertal or adrenarchal outcomes in girls. Paternal obesity alone was not associated with any outcomes in either boys or girls. Biparental obesity was associated with earlier age at PHV in boys and earlier menarche in girls. Using marginal structural models with stabilized inverse probability weighting, maternal obesity alone had significant controlled direct effects on age at PHV (-0.31 years; -0.62, 0.00) and on pubertal score (0.22 units; 0.00, 0.44) in boys, independent of prepubertal BMI. CONCLUSION: Maternal, but not paternal, obesity is associated with earlier pubertal development in boys, and such association is independent of prepubertal BMI.

Dynamic regime marginal structural mean models for estimation of optimal dynamic treatment regimes, Part II: proofs of results.

In this companion article to "Dynamic Regime Marginal Structural Mean Models for Estimation of Optimal Dynamic Treatment Regimes, Part I: Main Content" [Orellana, Rotnitzky and Robins (2010), IJB, Vol. 6, Iss. 2, Art. 7] we present (i) proofs of the claims in that paper, (ii) a proposal for the computation of a confidence set for the optimal index when this lies in a finite set, and (iii) an example to aid the interpretation of the positivity assumption.