a retrospective population-based cohort study finds. Risks appeared highest with first-trimester syncope.
“There are very limited data on the frequency of fainting during pregnancy,” Padma Kaul, Ph.D., senior study author and professor of medicine at the University of Alberta, Edmonton, said in a statement. “In our study, fainting during pregnancy occurred in about 1%, or 10 per 1,000 pregnancies, but appears to be increasing by 5% each year.”
“Fainting during pregnancy has previously been thought to follow a relatively benign course,” Dr. Kaul said. “The findings of our study suggest that timing of fainting during pregnancy may be important. When the faint happens early during pregnancy or multiple times during pregnancy, it may be associated with both short- and long-term health issues for the baby and the mother.”
First authors Safia Chatur, MD, of the University of Calgary (Alta.) and Sunjidatul Islam, MBBS, of the Canadian Vigour Centre, Edmonton, Alta., and associates analyzed 481,930 pregnancies occurring during 2005-2014 in the province.
Study results, reported in the, showed that syncope occurred in almost 1% of pregnancies (9.7 episodes per 1,000 pregnancies) overall. Incidence increased by 5% per year during the study period.
Syncope episodes were distributed across the first trimester (32%), second trimester (44%), and third trimester (24%). Eight percent of pregnancies had more than one episode.
Compared with unaffected peers, women who experienced syncope were younger (age younger than 25 years, 35% vs. 21%; P less than .001) and more often primiparous (52% vs. 42%; P less than .001).
The rate of preterm birth was 18%, 16%, and 14% in pregnancies with an initial syncope episode during the first, second, and third trimester, respectively, compared with 15% in pregnancies without syncope (P less than .01 across groups).
With a median follow-up of about 5 years, compared with peers of syncope-free pregnancies, children of pregnancies complicated by syncope had a higher incidence of congenital anomalies (3.1% vs. 2.6%; P = .023). Incidence was highest in pregnancies with multiple episodes of syncope (5% vs. 3%; P less than .01).
In adjusted analyses that accounted for multiple pregnancies in individual women, relative to counterparts with no syncope during pregnancy, women who experienced syncope during the first trimester had higher odds of giving birth preterm (odds ratio, 1.3; P = .001) and of having an infant small for gestational age (OR, 1.2; P = .04) or with congenital anomalies (OR, 1.4; P = .036). Women with multiple syncope episodes versus none were twice as likely to have offspring with congenital anomalies (OR, 2.0; P = .003).
Relative to peers who did not experience syncope in pregnancy, women who did had higher incidences of cardiac arrhythmias (0.8% vs. 0.2%; P less than .01) and syncope episodes (1.4% vs. 0.2%; P less than .01) in the first year after delivery.
“Our data suggest that syncope during pregnancy may not be a benign occurrence,” Dr. Chatur and associates said. “More detailed clinical data are needed to identify potential causes for the observed increase in syncope during pregnancy in our study.“Whether women who experience syncope during pregnancy may benefit from closer monitoring during the obstetric and postpartum periods requires further study,” they concluded.
The investigators disclosed no relevant conflicts of interest. This study was funded by a grant from the Cardiac Arrhythmia Network of Canada.
SOURCE: Chatur S et al.