Table 3.
Mediation of Maternal Obesity Consequences on the Association Between Early Pregnancy Body Mass Index and Risk of Early-onset Neonatal Sepsis
| HR (95% CI) | ||||||
|---|---|---|---|---|---|---|
| Potential Mediator | BMIa Association in Levels of Mediator, HR (95% CI) | P Value for BMI–Mediator Interaction | Total BMI Associationb | Direct BMI Associationc | Indirect BMI Association Through Mediator | Percentage of BMI Association Mediatedd |
| Gestational diabetes | ||||||
| No | 1.55 (1.43–1.68) | .90 | 1.56 (1.44–1.68) | 1.55 (1.43–1.67) | 1.01 (1.00–1.01) | 1.7 |
| Yes | 1.51 (1.00–2.27) | |||||
| Preeclampsia | ||||||
| No | 1.50 (1.38–1.63) | .0008 | 1.54 (1.42–1.66) | 1.47 (1.35–1.59) | 1.05 (1.04–1.06) | 13.7 |
| Yes | 1.03 (.84–1.27) | |||||
| Maternal infections | ||||||
| No | 1.57 (1.45–1.70) | .57 | 1.56 (1.45–1.68) | 1.56 (1.45–1.68) | 1.00 (1.00–1.00) | 0.0 |
| Yes | 1.45 (1.10–1.90) | |||||
| Premature rupture of membranes | ||||||
| No | 1.61 (1.48–1.74) | .001 | 1.57 (1.45–1.69) | 1.55 (1.44–1.67) | 1.01 (1.01–1.01) | 2.8 |
| Yes | 1.10 (.89–1.37) | |||||
| Prolonged labor | ||||||
| No | 1.56 (1.45–1.68) | .68 | 1.56 (1.45–1.68) | 1.56 (1.45–1.68) | 1.00 (1.00–1.00) | 0.0 |
| Yes | 1.83 (.86–3.89) | |||||
| Elective cesarean section | ||||||
| No | 1.58 (1.45–1.72) | .01 | 1.56 (1.45–1.69) | 1.52 (1.41–1.65) | 1.02 (1.02–1.03) | 6.6 |
| Yes | 1.24 (1.05–1.48) | |||||
| Emergency cesarean section | ||||||
| No | 1.50 (1.37–1.64) | .05 | 1.55 (1.44–1.68) | 1.45 (1.34–1.58) | 1.07 (1.05–1.08) | 17.9 |
| Yes | 1.26 (1.09–1.46) | |||||
| Preterm delivery | ||||||
| No | 1.74 (1.57–1.92) | <.0001 | 1.56 (1.45–1.68) | 1.49 (1.39–1.61) | 1.04 (1.04–1.05) | 11.7 |
| Yes | 1.20 (1.07–1.34) | |||||
| Any congenital malformations | ||||||
| No | 1.57 (1.45–1.70) | .34 | 1.56 (1.44–1.68) | 1.54 (1.43–1.67) | 1.01 (1.01–1.01) | 2.2 |
| Yes | 1.41 (1.15–1.73) | |||||
| Macrosomia (birth weight ≥4000 g) | ||||||
| No | 1.57 (1.44–1.71) | .77 | 1.55 (1.43–1.67) | 1.55 (1.43–1.67) | 1.00 (1.00–1.00) | 0.0 |
| Yes | 1.61 (1.36–1.90) | |||||
| Meconium aspiration | ||||||
| No | 1.55 (1.43–1.67) | .49 | 1.56 (1.44–1.68) | 1.54 (1.43–1.66) | 1.01 (1.01–1.01) | 2.6 |
| Yes | 1.30 (.81–2.10) | |||||
HRs and 95% CIs from multivariable-adjusted Cox proportional hazards models. One model was fitted with each potential mediator. BMI–mediator associations were modeled with multivariable logistic regression. Covariates included maternal age, country of origin, education level, cohabitation with a partner, parity, height, year of delivery, smoking during pregnancy, and infant’s sex. A BMI–mediator interaction term was tested and retained if statistically significant at P < .05. All effects on sepsis are estimated for a 10-kg/m2 BMI difference from a baseline level of 23.1 kg/m2 at the reference category of each covariate.
Abbreviations: BMI, body mass index; CI, confidence interval; HR, hazard ratio.
aBMI calculated as weight in kilograms divided by height in meters squared.
bTotal effect estimates may vary between models for different mediators due to differences in the number of missing values for each mediator and exposure–mediator interactions. They may differ from estimates by levels of the mediator, even in the absence of interaction, due to noncollapsibility.
cEstimated at mediator level “no.”
dSum of percentages is not necessarily 100 because the effects of mediators are not mutually exclusive, mediators could interact with one another, and not all mediators may have been considered.