Women with Mitochondrial Disease More Prone to Pregnancy Complications, Study Shows

Joana Carvalho, PhD avatar

by Joana Carvalho, PhD |

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Pregnancy and mitochondrial disease

Women with mitochondrial disease or mitochondrial dysfunction are more susceptible to complications during pregnancy, and their newborns are more likely to have congenital defects, a retrospective study shows.

The study, “Effects of mitochondrial disease/dysfunction on pregnancy: A retrospective study,” was published in Mitochondrion.

Primary mitochondrial disease (MD) comprises several rare disorders caused by genetic mutations in nuclear and mitochondrial DNA, whereas mitochondrial dysfunction (Md) may develop through environmental exposure, medications, infection or other non-genetic factors.

Both MD and Md lead to mitochondria malfunction, in particular decreased production of adenosine triphosphate (ATP) — the energy molecule used by all cells in the body — by the mitochondrial respiratory chain (MRC), which has a direct impact on cell function.

During pregnancy, metabolic demands increase to allow fetal development and growth, which requires optimal and efficient energy production. But there is little information regarding the impact of pregnancy on women with MD/Md who might not be able to sustain normal energy production and have, in theory, a higher chance of pregnancy complications.

In this study, authors analyzed obstetric effects and potential complications in women with MD/Md and their children to gather information that could help improve maternal and fetal outcomes in MD/Md in the future.

The study analyzed 103 women diagnosed with MD/Md between 16 and 75 years old who had been pregnant at least once. Information about their demographic backgrounds, gynecological history, fertility, pregnancy history, postnatal issues, MD/Md symptoms and use of dietary supplements was gathered in online surveys.

Most were Caucasian (94.2%) and were diagnosed with mitochondrial myopathy (34%). A total of 370 pregnancies (average 3.6 pregnancies/woman), with 248 leading to live deliveries, were reported by the women.

In 68.1% of all pregnancies, newborns were delivered vaginally at an average gestational age of 38.2 weeks, within the normal range of 38 to 42 weeks. But 10.9% of these newborns had breathing difficulties, and 8.4 percent were diagnosed with congenital defects, mostly associated with heart problems.

On average, the women had their first period at age 13, nearly identical to the general U.S. population (12.5 years old), first got pregnant at 24.4 years old, and 46.6% said they had at least one miscarriage during the first or second trimester (average loss was 2.4 pregnancies/woman).

Most (78%) experienced pregnancy complications with varying degrees of severity, including vaginal bleeding (37.9%), abnormally high levels of proteins in the urine (26.2%), high blood pressure (24.3%), gestational diabetes (23.3%), fetuses who were small for gestational age (21.4%), and pre-eclampsia (18.4%).

In general, pregnancy seemed to worsen chronic MD/Md symptoms, including shortness of breath, low blood pressure, tachycardia (heart rhythm disorder), constipation, exercise intolerance, muscle weakness, headaches, balance problems, anemia, and anxiety/depression.

The findings indicate that MD/Md tends to exacerbate women’s disease symptoms during pregnancy and raise the likelihood of common gestation complications, but all these effects do not appear to lead to drastically worse pregnancy outcomes.

“[These findings] highlight the need for future studies to better assess complications and health concerns of pregnant women affected with primary mitochondrial disease and how they differ from mitochondrial dysfunction in a larger population of patients. In the future, a multi-center prospective analysis of pregnant women with MD may aid in providing more concrete information about the specific risks of complications during pregnancy when compared to a healthy cohort of females,” the researchers wrote.