Reproductive
Coffee Consumption and Risk of Spontaneous Abortion in a Preconception Cohort Study Martha Koenig* Martha Koenig Amelia Wesselink David Savtiz Kenneth Rothman Lauren Wise Elizabeth Hatch
Background: Coffee consumption during pregnancy has long been studied as a potential risk factor for spontaneous abortion (SAB, pregnancy loss at <20 weeks gestation). Nausea and vomiting in early pregnancy (NVP) may lead people to reduce coffee intake. Additionally, NVP is associated with a reduced risk of SAB. Previous research has underscored the role of reverse causation when measuring this association, as non-viable pregnancies may allow continuing coffee consumption, causing upward bias.
Methods: We analyzed data from Pregnancy Study Online (PRESTO), an online preconception cohort study, to examine associations between coffee intake and risk of SAB. We collected information on coffee consumption and NVP on the early pregnancy questionnaire (EPQ). We identified incident SABs on the late follow-up questionnaire. We fit multivariable-adjusted Cox models with weeks of gestation as the time scale to estimate hazard ratios (HRs) for the effect of coffee intake on SAB and 95% CIs. In our main analyses, we restricted our sample to those who completed the EPQ at ≥6 weeks gestation, the typical time of NVP onset, and ≤10 weeks gestation.
Results: The HR for ≥1 cups/day (vs. none) was 1.26 (CI: 0.92, 1.73). Among those with NVP, coffee intake was positively associated with SAB (HR for ≥1 cups/day [vs. none] 1.41 (CI: 0.95, 2.07)); for those without NVP, coffee intake was not associated with SAB (HR=0.97 (CI: 0.56, 1.68)). When results were stratified by gestational week at time of EPQ completion, HRs for ≥1 cups/day (vs. none) were 1.16 (CI: 0.86, 1.56), 0.96 (CI: 0.55, 1.67), 1.43 (CI: 0.79, 2.58), 1.03 (CI: 0.46, 2.28), 1.71 (CI: 0.74, 3.97) and 1.34 (CI: 0.53, 3.38) for <6, 6, 7, 8, 9 and ≥10 gestational weeks, respectively.
Conclusion: Coffee intake showed little consistent association with SAB incidence. Sustained coffee consumption beyond 7 weeks gestation may be influential to understanding associations.
