COVID-19 pandemic waves and risk of congenital anomalies in the State of
Sao Paulo: a population-based cohort study.
Abstract
Objectives To assess how the COVID outbreak in Brazil might
have impacted birth defects in the State of São Paulo. Design
Population-based cohort study. Setting The State of São Paulo,
in Brazil. Population Births between 2017 and 2022.
Methods Exposure was determined by the midpoint of the first
trimester. We used a generalized linear model with Poisson distribution
and log link, with clustered robust standard errors. Municipality was
used for clustering. Main Outcome Measures The Relative Risk
(RR) for any congenital anomaly and per each anatomical site.
Results There were 2,961,741 cases in the analysis. The RR for
congenital anomalies was 0.97 in the first wave (95% CI: 0.95-1.00, p =
0.029) due to a decrease in respiratory, genitourinary and central
nervous system defects, a pattern previously associated with
fever-induced anomalies. During the third wave, there was an RR of 1.08
(95% CI: 1.04-1.13, p < 0.001), with an increase in cleft lip
and palate, digestive and circulatory defects, just as severe food
insecurity rose. No change in risk was identified during the second
wave, when both vaccines were introduced and the sales of ivermectin and
hydroxychloroquine spiked. Conclusions The COVID-19 outbreak
impacted birth defects differently during each wave. Considering
concurrent conditions might provide insight into the underlying causes
for this phenomenon. The true burden for pregnant individuals of food
supply chain disruption, which is also threatened by climate change,
might not yet be fully recognized.