CV. Short-term outcome of pregnant women vaccinated by BNT162b2 mRNA COVID-19 vaccine


Bookstein Peretz Shiran et al. Short‐term outcome of pregnant women vaccinated with BNT162b2 mRNA COVID‐19 vaccine – Bookstein Peretz – – Ultrasound in Obstetrics & Gynecology – Wiley Online Library

Recopilado por Carlos Cabrera Lozada. Director del postgrado de Medicina Materno Fetal. Universidad Central de Venezuela. ORCID: 0000-0002-3133-5183. 13/08/2021

Objective: To determine the immunogenicity and reactogenicity of Pfizer’s BNT162b2 COVID-19 vaccine among pregnant women compared with non-pregnant women, and to evaluate the obstetric outcome following vaccination. Methods: An observational case-control study of pregnant women, who were vaccinated by a 2-dose regimen of BNT162b2 vaccine during gestation between January-February 2021 (study group) and were compared to age-matched nonpregnant women who received the vaccine during the same time period (control group). Participants received a digital questionnaire 1-4 weeks after the second dose and were asked to provide information regarding demographics, medications, medical history, history of prior SARS-CoV-2 infection, the timing of COVID-19 vaccine doses, and side effects after each vaccine dose. A second digital questionnaire, regarding current
pregnancy and delivery outcomes, was sent to patients of the study group after the calculated due date. All recruited patients were offered a serology blood test for SARS CoV-2 IgG following the second vaccination dose, and SARS CoV-2 IgG levels were compared between the two groups. Results: Of 539 pregnant women who were recruited after completion of the 2-dose regimen of the vaccine, 390 returned the digital questionnaire and were included in the study group and compared to 260 age-matched non-pregnant women. The rate of most of the adverse events among pregnant women following vaccination was comparable to non-pregnant women except for myalgia, arthralgia, and headache which were significantly less common among pregnant women after each dose, and paresthesia, which was more common among the pregnant population after the second dose. There were no significant differences in the rates of side effects when receiving the vaccine at the first, second, or third trimester of pregnancy. The rate of obstetrical complications, including uterine contractions (1.3% after the first dose and 6.4% after the second dose), vaginal bleeding (0.2% after the first dose and 1.5% after the second dose), and premature rupture of membranes (0% after the first dose and 0.7% after the second dose) were extremely low following vaccination.

All maternal sera samples in both groups were positive for SARS-CoV-2 IgG. However, pregnant women had significantly lower serum SARS-CoV-2 IgG levels compared to those of non-pregnant women (signal-to-cut-off ratio, 27.03 vs 34.35, respectively; P < 0.001). Among the 57 pregnant women who delivered during the study period and who completed the second questionnaire, the median gestational age at delivery was 39.5 (interquartile range, 38.7–40.0) weeks, with no cases of preterm birth < 37 weeks, no cases of fetal or neonatal death and two (3.5%) cases of admission to the neonatal intensive care unit for respiratory support.


The adverse-effect profile and short-term obstetric and neonatal outcomes among pregnant women who were vaccinated with the BNT162b2 vaccine at any stage of pregnancy do not indicate any safety concerns. The vaccine is effective in generating a humoral immune response in pregnant women, although SARS-CoV-2 IgG levels were lower than those observed in non-pregnant vaccinated women. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

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