The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 54

68. How does mast cell disease affect pregnancy?

One of the things mast cells normally do in the body is regulate the female reproductive cycle. Mast cells in the endometrium, the uterine lining that is shed during menstruation, become activated and release mediators in the days before and during menstruation. Many of the symptoms of premenstrual syndrome (PMS) occur because of mast cell degranulation. These symptoms include things like cramps and bloating.

Because mast cells are involved in controlling the reproductive cycle, they are responsive to the effects of hormones like estrogen and progesterone. In particular, estrogen can directly cause mast cell degranulation.

In some allergic conditions like asthma, patients often have flares right before or during their menstrual period. This is often the case with mast cell patients as well. The change in hormones, the built in mast cell activation, and the bleeding, can all cause mast cell symptoms.

A study on the effects of the pregnancy on mastocytosis found that there was a lot of variability in what patients experienced. 33% of women had symptom improvement during pregnancy. In these women, their symptoms mostly improved beginning in the first trimester and continued throughout their pregnancy. 45% of patients had no change in symptoms during pregnancy. The remainder had worsened symptoms.

Mastocytosis did not seem to affect the outcome of pregnancy compared to the normal population. Premedication was recommended at the start of labor. Many women safely received anesthesia. In women who reacted, 2/3 had not premedicated. Induction of labor with medication was well tolerated. Both vaginal delivery and Caesarean section was performed safely on women with mastocytosis. The frequency of Caesarean section, miscarriage, prematurity and low birth weight were similar to the general population.

In some instances, severe allergic reactions and anaphylaxis can induce early labor, so patients should be aware of this risk.  Histamine can trigger uterine contractions.

An important thing to consider is that mast cell patients may have to change or stop some of their medications while pregnancy to avoid effects upon the fetus. In particular, the use of epinephrine is discouraged in pregnancy because it causes uterine contractions. Mast cell patients should have an alternative plan for anaphylaxis that excludes epinephrine where possible. Any mast cell patient who is pregnant or considering becoming pregnant should have detailed discussions with their providers about it.

For more detailed reading, please visit the following posts:
Pregnancy in mastocytosis
Effects of estrogen and progesterone and the role of mast cells in pregnancy