Prepregnancy Low to Moderate Alcohol Intake Is Not Associated with Risk of Spontaneous Abortion or Stillbirth.

BACKGROUND Numerous studies have documented the negative effects of maternal alcohol consumption during pregnancy on risk of pregnancy loss, yet whether prepregnancy alcohol intake affects the risk of spontaneous abortion is still unclear. OBJECTIVE This study aimed to assess prepregnancy alcohol intake and risk of spontaneous abortion and stillbirth. METHODS Our prospective cohort study included 27,580 pregnancies reported by 17,929 women in the Nurses' Health Study II between 1990 and 2009. Alcohol intake was assessed in 1989 and 1991 and every 4 y thereafter with the use of a validated questionnaire. Women were classified into 5 categories of consumption: 0, 0.1-1.9, 2-4.9, 5-9.9, and ≥10 g/d (1 serving = ∼12 g). Pregnancies were self-reported, with case pregnancies lost spontaneously (spontaneous abortion after gestation of <20 wk and stillbirth after gestation of ≥20 wk) and comparison pregnancies not ending in fetal loss (live birth, ectopic pregnancy, or induced abortion). Multivariable log-binomial regression models with generalized estimating equations were used to estimate RRs and 95% CIs. RESULTS Incident spontaneous abortion and stillbirth were reported in 4326 (15.7%) and 205 (0.7%) pregnancies, respectively. Prepregnancy alcohol intake was not associated with spontaneous abortion. Compared with women who did not consume alcohol, the multivariable RRs (95% CIs) for increasing categories of alcohol intake among women who did consume alcohol were 1.04 (0.97, 1.12) for 0.1-1.9 g/d, 1.02 (0.94, 1.11) for 2-4.9 g/d, 1.01 (0.92, 1.10) for 5-9.9 g/d, and 0.98 (0.88, 1.09) for ≥10 g/d (P-trend = 0.45). Women who consumed ≥2 servings beer/wk before pregnancy had a 9% (95% CI: 1%, 17%) lower risk of spontaneous abortion than did women who consumed <1 serving beer/mo; however, this association did not persist in various sensitivity analyses. Prepregnancy consumption of wine and liquor were not associated with spontaneous abortion. Total alcohol and specific alcohol beverage intake before pregnancy were not associated with stillbirth. CONCLUSION Prepregnancy alcohol intake was not related to risk of incident spontaneous abortion or stillbirth in women with no history of pregnancy loss. Our results provide reassuring evidence that low to moderate alcohol intake (≤12 g/d) before pregnancy initiation does not affect risk of pregnancy loss.