Q&A: Maternal oxygen supplementation in childbirth may be unnecessary for most

Although maternal oxygen supplementation during labor and delivery is common to prevent hypoxia and acidemia in the fetus, it may be unnecessary, according to research published in JAMA Pediatrics.

Currently, the American College of Obstetricians and Gynecologists recommends maternal oxygen supplementation as an intrauterine resuscitation technique to help manage fetal heart rate during childbirth.

To assess whether maternal oxygenation affected neonatal outcomes, researchers conducted a systematic review and meta-analysis of randomized clinical trials that compared maternal oxygen supplementation and room air during delivery in women with singleton births. Trials were excluded if they did not collect paired umbilical artery gas samples or measured umbilical artery pH or Pao₂.

A total of 16 randomized clinical trials were included in the meta-analysis. The researchers determined that significant heterogeneity existed among these studies.

Researchers reported that, overall, oxygen administration to mothers during childbirth was not associated with a significant difference in umbilical artery pH (weighted mean difference = 0.00; 95% CI, 0.01 to 0.01).

They also found that oxygenation was associated with increased umbilical artery Pao₂, but they did not find a significant difference in umbilical artery base excess, umbilical artery pH below 7.2 — which is considered abnormal and points to oxygen deprivation — Apgar scores that evaluate newborn health at 1 and 5 minutes after birth, or neonatal ICU admissions.

After accounting for risk of bias, oxygen delivery device and fraction of inspired oxygen, researchers found that umbilical artery pH values stayed similar between those who received oxygen supplementation and those only exposed to room air.

In an analysis stratified by whether women experienced labor, researchers found that supplemental oxygen administration in women who had a scheduled cesarean delivery was associated with increase umbilical artery Pao₂ (weighted mean difference = 2.12 mmHg; 95% CI, 0.09-4.15mmHg) and reduced incidence of umbilical artery pH below 7.2 (RR = 0.63; 95% CI, 0.43-0.90). However, they found that these differences were not observed in women who experienced labor.

Researchers noted that the findings suggest that maternal oxygen supplementation during childbirth was not associated with clinically relevant neonatal outcomes.

Healio Primary Care spoke with study author Nandini Raghuraman, MD, MS, assistant professor in the division of maternal-fetal medicine in the department of obstetrics and gynecology at Washington University in St Louis, to learn more about the findings and whether guidance on maternal oxygen supplementation in childbirth should be changed.

Q: How common is maternal oxygen supplementation during labor and delivery?

A: Two out of three laboring mothers in the United States will receive oxygen at some point in their labor. This equates to over 1.5 million women and their babies receiving extra oxygen in labor.

Q: How do these findings differ from previous research on the need for supplemental oxygen in women during labor and delivery?

A: The previous research on oxygen during labor had mixed results. Some suggested benefit, some suggesting no benefit and others suggesting potential harm. The strength of this type of a study, a meta-analysis, is that it pools the results from all of the above studies which provides strength in numbers. You can make a more meaningful conclusion with data from more patients. Our results show that oxygen administration given in response to the baby’s heart rate in labor is unlikely to help.

Q: Based on the findings, should ACOG change their recommendation on maternal supplemental oxygen in labor and delivery? Why or why not?

A: The findings of this study should prompt providers to readdress the need for oxygen. I think we still have some unanswered questions before formal changes to guidelines and recommendations can be made. We need more research on the impact of oxygen on the health of the mother and baby, besides the lab values we studied. We should study the serious consequences of not having enough oxygen in labor or having too much oxygen in labor. Just like any other drug, we must find the right dose and duration, if any at all, that could be helpful.

Q: What are the potential health effects to mothers who receive unnecessary supplemental oxygen during childbirth?

A: Currently, we do not have enough research in pregnant women to answer this question. There is some research that suggests that the mother’s vital signs change in response to too much oxygen, but we don’t know much about what this means for the mother’s overall health. Outside of pregnancy, there is plenty of research to suggest that over-oxygenation is harmful. Too much oxygen leads to free radicals which can cause cell damage. This process has been linked to many chronic conditions such as Alzheimer’s disease, heart disease and retinal degeneration.

Q: What additional research is needed to assess the effects of maternal oxygen supplementation during childbirth on maternal and fetal health?

A: We need additional research on the downstream impact of over-oxygenation on the mother and baby. Our study shows that umbilical cord gases, a reflection of the baby’s oxygenation status at birth, are not impacted. However, we need more data on the baby’s health following delivery. We also need more answers about whether this practices actually improves the baby’s heart rate. The current standard of care is to give mother’s 10 liters of oxygen a minute through a mask. We should also research if there is a different dose or duration of oxygen exposure that may be helpful or that minimizes harm.

References:

Newswise. For moms, oxygen during childbirth often unnecessary. https://www.newswise.com/articles/for-moms-oxygen-during-childbirth-often-unnecessary2?ta=home. Accessed January 8, 2021.

Raghuraman N, et al. Name, et al. JAMA Pediatr. 2021;doi:10.1001/jamapediatrics.2020.5351.