Growth trajectories among infants with vs without in utero COVID-19 exposure

By Bhavana KunkalikarReviewed by Danielle Ellis, B.Sc.Apr 3 2023

In a recent study published in The Journal of Clinical Endocrinology & Metabolism, researchers explored longitudinal weight gain in infants who were exposed to in-utero coronavirus disease 2019 (COVID-19).

Background

A demographic of children, who have been exposed to maternal COVID-19 in utero, has emerged, given that pregnant women account for 9% of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected women of reproductive age. The potential ramifications of maternal COVID-19 during pregnancy on the well-being of future generations have not been extensively studied.

However, considering the potential impact of the intrauterine environment on the long-term health of offspring, it is imperative to investigate the varying growth patterns and related risks of cardiometabolic diseases among in-utero COVID-19-exposed children.

About the study

In the present study, researchers conducted a comparative analysis of the longitudinal growth trajectories of infants who were and were not exposed to COVID-19 in utero.

The Mass General Brigham (MGB) COVID-19 Perinatal Biorepository was employed to compare longitudinal growth trajectories during the initial 12 months of life between infants exposed to maternal COVID-19 in utero and those who were not. This was performed for mothers who have contracted or are at risk of contracting COVID-19 and their neonates.

The inclusion criteria for the study involved pregnant females aged 18 years and above seeking medical care at Massachusetts General Hospital (MGH). The diagnosis of maternal COVID-19 was primarily established through the use of nasopharyngeal swabs for a reverse transcription-polymerase chain reaction (RT-PCR).

The comparator group consisted of mothers with no recorded prenatal COVID-19 history and tested SARS-CoV-2 negative via RT-PCR during universal screening at the time of delivery. The present study is centered on a specific group of neonates delivered by mothers enrolled in the MGB COVID-19 Perinatal Biorepository.

Longitudinal anthropometric data was collected on eligible infants over their initial year of life with electronic medical records. Anthropometric measurements, including weight, length, and body mass index (BMI), were obtained at birth, two months, six months, and 12 months. The utilization of raw data was employed to compute z-scores that were adjusted for age and sex, utilizing growth charts sourced from the World Health Organization (WHO).

Furthermore, birth length and weight z-scores were also estimated according to Fenton growth charts. Newborns were categorized as having low birth weight (LBW) if their birth weight was less than 2.5 kg and as small for gestational age (SGA) if their Fenton birth weight z-score was below the 10th percentile.

Results

No significant differences were observed in terms of prenatal age, tobacco usage, gestational diabetes, gestational hypertension, and obesity between mothers who had prenatal COVID-19 and those who did not. The cohort under study revealed that mothers who contracted COVID-19 predominantly exhibited mild symptoms and were diagnosed during the third trimester of pregnancy. The vast majority of individuals included in the study had a prior breastfeeding history, regardless of their COVID-19 exposure status.

The study aimed to compare the length, weight, and BMI z-scores noted at birth between infants exposed to COVID-19 in utero and those not. Offspring born to mothers exposed to COVID-19 during pregnancy demonstrated reduced birth weight z-score and BMI z-score compared to unexposed control groups.

There was a correlation between exposure to COVID-19 in utero and reduced BMI, and weight z-scores at birth remained significant even after controlling for various factors such as maternal age at delivery, parity, ethnicity, earliest BMI during pregnancy, as well as infant sex and birth date.

There were significant differences in the BMI and weight z-scores trajectories of infants born to mothers with prenatal COVID-19 compared to those without. This difference was observed from birth up to 12 months of age. These dissimilarities were resilient in multivariate models that accounted for the infant and maternal covariates incorporated in the birth analyses.

The study found no significant variation in the length z-score trajectories based on COVID-19 exposure status. This observation remained consistent even after adjusting for gestational age. Furthermore, the study found no association between in-utero COVID-19 exposure and length at birth.

The study found that regardless of the study group, a greater alteration in BMI z-score between birth to 12 months was associated with a lower birth weight z-score among the overall sample. The mediation analysis results revealed that the birth weight z-score acted as a mediator in a substantial portion of the impact of COVID-19 exposure on the alteration of BMI z-score from birth to 12 months. This suggested a possible mechanistic function of birth weight z-score in this context.

Conclusion

The study findings revealed that neonates exposed to maternal COVID-19 during the gestational period manifested reduced birth weight and BMI, as well as accelerated postnatal weight gain compared to those who were not exposed.

The study also suggested that there may be a heightened risk of cardiometabolic disease among the significant number of children worldwide who were exposed to COVID-19 while in utero. As a result, these individuals must receive ongoing monitoring throughout their lifespan.