evidence: A large prospective cohort study including 7809 pregnant people found that covid-19 vaccines were well tolerated among people who were pregnant, lactating, or planning pregnancy. Odds of several reactions were decreased among people who were pregnant, such as fever after Pfizer dose 2 (odds ratio 0.44, 0.38 to 0.52; P<.001) and after Moderna dose 2 (0.48, 0.40 to 0.57; P<0.001) compared with those who were neither pregnant nor lactating.55 The frequency of complaints after vaccination was similar to that observed in non-pregnant patients, and reports of adverse outcomes were infrequent. Additionally, a prospective study of 83 vaccinated pregnant women who were age matched with 166 vaccinated female non-pregnant controls found the frequency of complaints following vaccine administration did not differ between pregnant and non-pregnant patients (18.1% v 16.9%; P=0.20).82 However, pregnant patients were more likely to report fever (4.8% v 0.6%; P=0.04) and gastrointestinal symptoms (4.8% v 0%; P=0.01). This could reflect differences in the physiologic responses to the vaccines in pregnancy.