MS Bears No Effect on Certain Pregnancy Complications, Stillbirth, or Congenital Deformation

Frieda Wiley, PharmD

February 08, 2021

Multiple sclerosis (MS) may not pose a higher risk for complications in pregnant women, according to a new study published online Feb. 3 in Neurology Clinical Practice. While pregnancy and childbirth are not regarded as conditions that engender high-risk pregnancy in the MS population, previous studies evaluating the effects of MS on pregnancy and parturition have yet to fully elucidate some outcomes for pregnant women and their babies in multiple sclerosis.

"Women with multiple sclerosis may be understandably concerned about the risk of pregnancy," said Melinda Magyari, MD, PhD, a consultant at the University of Copenhagen. "While previous research has shown there is no higher risk of birth defect for babies born to women with MS, we wanted to find out if women with MS are at risk for a variety of pregnancy complications."

MS is regarded as a progressive, neurological disease mediated by the immune system that demands careful consideration of numerous situations and life changes including family planning. The MS population is overwhelmingly female, as women account for three out of every four cases of MS. The majority of these women range from 20 to 40 years of age at the time of being diagnosed with MS. Despite the unknown risks of pregnancy-related complications and various perinatal complications in this patient population, women who have MS are not discouraged from conceiving.

Assessing Pregnancy Outcomes

This nationwide, population-based, cross-sectional study evaluated the pregnancies of 2,930 women with MS between Jan. 1, 1997, and Dec. 31, 2016, registered in the Danish Multiple Sclerosis Registry. The researchers compared pregnancy-related and prenatal outcomes to a 5% random sample of 56,958 randomly-selected pregnant women from Denmark's general population who did not have MS.

They found no differences in the risks associated with several pregnancy-related complications (e.g., preeclampsia, gestational diabetes, or placental complications), emergency Cesarean section (C-section), instrumental delivery, stillbirth, preterm birth, or congenital malformation. Apgar scores were low in both groups. A composite of various biometrics in newborns such as reflexes, muscle tone, and heart rate immediately following birth, the Apgar score is used to help assess the neonatal health, with a value of less than 7 considered low. Here, preterm birth is defined as delivery occurring before 37 weeks of gestation, and stillbirth describes a fetus born dead after 22 weeks of gestation.

Women in the MS cohort were more likely to have elective C-sections (odds ratio, 2.89 [95% confidence interval, 1.65-2.16]), induced labor (OR, 1.15 [95%CI, 1.01-1.31]) and have babies with low birth weight based on their gestational age (OR, 1.29 [95% CI, 1.04-1.60]). Nearly 30% of babies born in the cohort (n = 851) were born to mothers who had received disease-modifying therapy (DMT).

Neonates exposed to DMT weighed an average of 116 g less than babies born to mothers who had not received DMT (3,378 g vs. 3,494 g) with a slightly lower gestational age (39 weeks as opposed to 40 weeks). However, babies born to mothers with MS were less likely to show signs of asphyxia (OR, 0.87 [95% CI, 0.78-0.97]) than the comparison cohort.

"We found overall, their pregnancies were just as healthy as those of the moms without MS," Magyari said.

Comprehensive Data

Denmark's health care system has two key features that make it an attractive setting in which to conduct such a study — the first being its universal health care. The second advantage is that the country enacted several health registries in the 1970s and 1980s that enable the collection of more comprehensive data. For example, the Danish National Patient Register is a population-based registry that spans the entire nation, facilitating epidemiological research with what the study's authors describe as "high generalizability."

Providing additional insights regarding the patient story helps add context to pregnancy and outcomes. Among the data collected on the women studied were demographics, contact information, and abortions, both spontaneous and medically induced. The country uses other databases and registries to capture additional data.

For example, the Register of Legally Induced Abortions provides data regarding the context of medically induced abortions. In contrast, the Danish Medical Birth Registry provides context regarding specified variables regarding women's pregnancies, delivery, and perinatal outcomes. Finally, the population's education register offers information regarding patients' educational history.

A key strength of this study is that the long duration of follow-up data from the Danish Medical Birth Registry, along with its comprehensive data collection, eliminates recall bias. Universal access to health care also improves the generalizability of data. A limitation of the study is its lack of data on maternal smoking and its effects on low gestational weights. The study also has some data gaps, including body mass index information missing from a large portion of the cohort. Finally, the sample size of newborns born to mothers who had received DMT therapy within the last 6 months of gestation was too underpowered to stratify based on first on first-line or second-line treatment.

Magyari served on scientific advisory boards for Biogen, Sanofi, Teva, Roche, Novartis, and Merck. She has also received honoraria for lecturing from Biogen, Merck, Novartis, Sanofi, Genzyme, and has received research support and support for congress participation from Biogen, Genzyme, Teva, Roche, Merck, and Novartis. Coauthors disclosed various fees received from Merck, Novartis, Biogen, Roche, Sanofi Genzyme, and Teva.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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