Certain pregnancy complications — cesarean-section delivery, gestational diabetes, and preterm prelabour rupture of membranes — are more common among women diagnosed with inflammatory bowel disease than in the general population, according to a large study.
The study, “Systematic review with meta-analysis: risk of adverse pregnancy-related outcomes in inflammatory bowel disease,” was published in the journal Alimentary Pharmacology & Therapeutics.
Inflammatory bowel disease (IBD), a designation that includes Crohn’s disease (CD) and ulcerative colitis (UC), affects women in their fertile years. Symptoms usually appear from age 15 to 30, and about half of the patients are diagnosed before reaching 35. Estimates show that 25% of patients become pregnant after getting an IBD diagnosis.
Some studies have reported higher rates of cesarean section (C-section), gestational diabetes, and placenta-related disorders in women diagnosed with IBD. However, these findings are from studies with relatively small numbers of patients.
In the new study, researchers in Canada conducted a large systematic review based on previously published data to investigate whether women with IBD are at risk for pregnancy complications.
In total, they selected 53 studies that included 7,917 pregnancies from women with IBD and 3,253 from healthy women (controls).
The analysis showed that C-sections were more common among pregnant women with IBD — incidence of 32.5% — than in the general population, which had an incidence of 21%. C-sections were seen in 21.4% of women with UC and 28.9% with CD.
The risk of C-section delivery was 1.79-times higher for women with IBD compared with other women. However, this increased risk was only significant for women with UC and not with CD.
The researchers also explored whether medication used to manage IBD influenced pregnancy outcomes. Data from 708 IBD women on anti-tumour necrosis factor (TNF) treatment showed that C-section was performed on 49.6% of cases. Patients prescribed a combination therapy of an immunomodulator and anti-TNF were more likely to undergo C-sections.
Although disease activity was unknown, a higher rate of C-sections for more medicated patients indicates that this factor might be relevant for pregnancy outcome.
In the analysis, pregnancy-associated diabetes was diagnosed in 3.7% of women with IBD. Compared to the general population group, IBD women had a 2.96-times higher risk of developing diabetes during pregnancy. For this condition, the use of anti-TNF therapy and anti-inflammatory therapies, such as corticosteroids and the glucocorticoid budesonide, showed no correlation to gestational diabetes risk.
These findings support the need for “adherence to screening guidelines for gestational diabetes during pregnancy (ie testing at 24–28 weeks of gestational age) and optimising vitamin D levels,” to improve pregnancy outcomes in patients with IBD, the researchers wrote. However, “this remains to be determined in larger, prospective studies,” they added.
Preterm prelabour rupture of membranes or PPROM, a complication where the membrane that holds the amniotic liquid breaks before 37 weeks of gestation, was more prevalent in the IBD group. The researchers estimated that 8.5% of IBD pregnancies (14.2% in patients with CD) had PPROM, an increased risk of 12.1 compared to the healthy group.
Higher incidences of PPROM was found in IBD women exposed to anti-TNF therapy (3.4%) and those treated with thiopurines (2.7%) — drugs that inhibit the response of the immune system, known as immunosuppressants — compared with the non-exposed groups (0.3%). The risk among women treated with 5-aminosalicylic (5-ASA), a current standard treatment for IBD, was 21.4% compared to 5.9% in the non-exposed group.
The incidence of both preeclampsia (high blood pressure during pregnancy) and chorioamnionitis (an infection of the placenta and the amniotic fluid) was lower among women with IBD compared to those in the general population: preeclampsia affected 2.0% of IBD women (3.8% in UC and 1% in CD) vs 4.6% of the general population; chorioamnionitis was present in 0.3% of IBD women (0.4% in UC and 0.2% in CD) vs 4%.
Additionally, placenta-related complications, including placenta previa (low-lying placenta that covers the uterus cervix) and placental abruption (placenta separation from the uterus), showed no significant increase in pregnant women with IBD.
IBD therapies, including 5-ASA and anti-TNF, were not associated with an increased risk for placenta-related diseases.
Although based on a low number of studies, “these preliminary findings support recent guideline recommendations to continue anti-TNF therapy during pregnancy in order to maintain disease remission,” the researchers said.
“Our study demonstrates that patients with IBD are at the risk of adverse maternal and obstetric outcomes such as gestational diabetes and preterm prelabour rupture of membranes,” they wrote.
These findings highlight the need for pregnant women with IBD to be followed “by a multi-disciplinary team, including gastroenterologists, obstetricians and maternal-fetal medicine specialists in order to reduce overall pregnancy-related morbidity,” the study said.