Women with AS at greater risk of pregnancy complications: Study
Higher rates of gestational diabetes, fetal death found in large US study
Women with ankylosing spondylitis (AS) have a greater risk of pregnancy complications that can affect both the mother and the child than do those without the inflammatory condition, a U.S. population-based study found.
Among the maternal complications found were higher rates of cesarean delivery, gestational diabetes, or diabetes during pregnancy, and placenta previa — when the placenta blocks the birth canal. Key complications affecting the child were an increased risk of intrauterine fetal death and newborns being smaller at birth for their gestational age, or how far along in the pregnancy the baby is born.
“Women diagnosed with ankylosing spondylitis demonstrate a heightened occurrence of obstetrical complications,” the researchers wrote, noting that their team “examined a range of pregnancy and delivery complications, providing detailed insights that can enable physicians to offer more precise counseling to pregnant women diagnosed with AS.”
According to the researchers, “these results underscore the significance of thorough patient counseling, multidisciplinary care, and vigilant obstetric monitoring for individuals with AS throughout the course of their pregnancies.”
The population-based study, “Obstetric and neonatal outcomes in women with Ankylosing spondylitis — an evaluation of a population database,” was published in the journal BMC Pregnancy and Childbirth.
Investigating pregnancy complications specifically in AS
Ankylosing spondylitis is a type of arthritis characterized by long-term inflammation of the joints of the spine, typically the sacroiliac joints where the spine joins the pelvis. Over time, some of the bones in the spine fuse, making it stiff and inflexible, which can be debilitating for patients.
Most people with AS develop their first signs of the disease before age 45, with about 80% of patients experiencing symptoms before 30. In women, these symptoms often first occur during childbearing age.
However, there are conflicting data regarding pregnancy outcomes in these patients. Some studies have shown an increased risk of preterm labor or preeclampsia, a serious condition marked by high blood pressure, while others found no associated risks. Further, two previous large studies of spondylarthritis investigated all types of the condition without focusing on “the impact of specific diagnoses such as AS,” the team wrote.
Given the limited and conflicting data, a team led by scientists at McGill University in Canada sought to learn more. The researchers compared pregnancy outcomes among a large U.S. population of women with and without AS.
Data on pregnancies between 2004 and 2014 were sourced from the Healthcare Cost and Utilization Project Nationwide Inpatient Sample database, the largest inpatient database in the U.S.
Several outcomes were assessed: preeclampsia, preterm delivery, the type of delivery (vaginal or cesarean), gestational diabetes, hemorrhage (bleeding), baby size, maternal or fetal death, and placenta previa.
Of the more than 9 million pregnancies identified in the database, 383 women were diagnosed with AS either before or during pregnancy. This resulted in an overall AS prevalence of 4.2 per 100,000 in this population, which increased significantly between 2004 and 2014.
The researchers downplayed that jump, however, noting that “the apparent increase in prevalence is more likely to reflect changes in the rates of diagnosis rather than a true increase in the actual disease prevalence.”
Researchers use info from largest inpatient database in US
When compared, more women with AS were 35 or older when pregnant than those without AS (25.6% vs. 14.7%). Those with AS were also more likely to be ethnically white individuals (80.5% vs. 52.3%), have a higher income, and have private insurance (79.1% vs. 50.6%). Pregnancy with multiples (more than one baby at a time) was also more common (3.1% vs. 1.5%), as were disorders of the thyroid gland among the women (8.6% vs. 2.5%).
Other factors, such as tobacco smoking during pregnancy, illicit drug use, chronic high blood pressure, and pregestational diabetes — having diabetes before pregnancy — were comparable between the two groups.
The researchers then adjusted data for factors that could influence the results, including age, ethnicity, medical insurance type, income, thyroid disorders, and pregnancies with multiples.
After adjustments, women with an AS diagnosis were found to be 1.55 times more likely to have gestational diabetes and 3.6 times more likely to have placenta previa than those without AS. They were also 1.47 times more likely to have a cesarean delivery but 33% less likely to have a spontaneous vaginal delivery.
“Women with AS have an increased rate of [gestational diabetes] even after adjusting for potential confounders such as age and multiple pregnancies,” the researchers wrote, also noting that they “identified a significantly higher rate of placenta previa in the AS group.”
Other pregnancy and delivery outcomes were comparable between the groups, including preeclampsia, eclampsia or seizures due to preeclampsia, and placental separation. The rates of preterm delivery, needed blood transfusion, maternal death, infections, postpartum hemorrhage, and vein blood clots also were comparable between women with and without AS.
Due to our reliance on a population-based cohort, the outcomes of our study are applicable to the broader American population.
Regarding fetal outcomes, women with AS were 2.19 times more likely to have a newborn small for the baby’s gestational age and had a 3.46 times higher rate of intrauterine fetal death. However, given the small number of intrauterine fetal death cases in this population (less than 11), “it is hard to draw definitive conclusions regarding this finding,” the team noted. The rate of congenital anomalies was similar between groups.
The researchers cited their focus on only women with AS as one study strength, and noted that this study had “one of the largest cohorts [groups] to address this topic.” Nonetheless, firm conclusions regarding some of the researchers’ findings “will likely only be determined by much larger population studies.”
Overall, though, the team noted that “due to our reliance on a population-based cohort, the outcomes of our study are applicable to the broader American population.”
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