Atrial Fibrillation and Atrial Flutter in Pregnant Women—A Population‐Based Study

BACKGROUND: The goal of this study was to determine the prevalence of atrial fibrillation and atrial flutter (AF) in pregnant women and to examine the impact of AF on maternal and fetal outcomes. METHODS AND RESULTS: Between January 1, 2003 and December 31, 2013, there were 264 730 qualifying pregnancies (in 210 356 women) in the Kaiser Permanente Southern California hospitals, among whom AF was noted in 157 pregnancies (129 women; 61.3 per 100 000 women, or 59.3 per 100 000 pregnancies). Prevalence of AF (per 100 000 women) in white, black, Asian, and Hispanic women was 111.6, 101.7, 45.0, and 34.3, respectively. Older age was associated with higher odds of having AF. Compared to women <25 years of age, the odds ratio (OR) of AF was 4.1 in women age 30 to 34 years, 4.9 in women age 35 to 39 years, and 5.2 in women age ≥40. Odds of AF episodes were higher during the third trimester compared to the first trimester (OR, 3.2; 95% CI: 1.5–7.7). Among AF patients, adverse maternal cardiac events were rare—2 women developed heart failure and there were no strokes or systemic embolic events and no maternal death. There were 156 live births (99.4% of all pregnancies). Compared to women without AF, fetal birth weights were similar, but rate for neonates’ admission to the neonatal intensive care unit was higher (10.8% vs 5.1%; P=0.003). CONCLUSIONS: AF is rare in pregnant women. Certain factors such as increased maternal age and white race increase the odds of having AF. Major maternal and fetal complications are infrequent, albeit a source of concern.