Effects of the Omicron variant on perinatal outcomes in full-term neonates

BACKGROUND: Research of coronavirus disease (COVID-19) effects on newborns is ongoing. But the research of specific variant’s effects is none. This study analyzed the effects of the Omicron variant on the perinatal outcomes of full-term newborns during the Omicron wave period. METHODS: Between December 2021 and April 2022, this study was conducted on all newborns who visited a single center. We investigated due to the Omicron maternal infection maternal pregnancy complications, delivery methods, birth week, Apgar scores, neonatal resuscitation program requirement, whether respiratory support was required until 12 h after childbirth, suspicious infectious status, and mortality depending on maternal Omicron infection. RESULTS: A total of 127 neonates were enrolled, and 12 were excluded based on exclusion criteria. Sixteen neonates were born to mothers with a history of Omicron COVID-19, and 99 were born to non-infectious mothers. All infected mothers became infected in the 3rd trimester. Of the 16 mothers, seven were symptomatic, and four met the isolation criteria, according to Korean guidelines. The birth weight of newborns to mothers with a history of COVID and those without was 2.958 ± 0.272 kg and 3.064 ± 0.461 kg (p = 0.049), respectively. The 5-min Apgar score at childbirth was 9.29 ± 0.756 and 9.78 ± 0.460 for neonates born to symptomatic and asymptomatic mothers (p = 0.019), respectively. When compared with or without maternal self-isolation, neonates requiring respiratory support 12 h after birth demonstrated a significant difference (p = 0.014; OR, 10.275). Additionally, the presence or absence of transient tachypnea of the newborn showed a significant value (p = 0.010; OR 11.929). CONCLUSIONS: Owing to Omicron COVID-19, newborns were born with lower birth weight, low 5-min Apgar scores, and required respiratory support until 12 h after birth.