Using the data of pregnant women with systemic lupus erythematosus (SLE), researchers in China created a predictive model that identifies high-risk pregnancies in these women. The model could help clinicians estimate the risk of an adverse outcome early in the pregnancy and start special monitoring and treatment as soon as possible.
The study, “Prediction of fetal loss in Chinese pregnant patients with systemic lupus erythematosus: a retrospective cohort study,” was published in BMJ Open.
SLE is an autoimmune disease that mostly affects women of reproductive age. Women with SLE have an average fertility rate but have a higher frequency of complications during pregnancy than the general population.
Therefore, the possibility of predicting high-risk pregnancies during the first weeks of gestation would allow clinicians to provide consultation and treatment aimed at preventing adverse outcomes.
Different risk factors for fetal loss such as lupus nephritis, the occurrence of flares six months before pregnancy, low complement (a component of the immune system) levels, and low platelet counts have been proposed. However, the results vary from study to study.
A group of Chinese researchers analyzed the data of pregnant women diagnosed with SLE who were treated at a tertiary center in Shanghai from September 2011 to May 2017 to develop a model that predicts the risk of pregnancy complication among women with SLE.
There were 338 pregnancies included in the analysis. The average age at conception was 29.5 years; the patients had been diagnosed 5.7 years on average before becoming pregnant. Also, 86.1% had not had children before.
The investigators measured parameters such as the mother’s age at the birth of her child, history of abortions, SLE activity before pregnancy, complete blood count, serum albumin, levels of protein in the urine, members of the complement C3 and C4, and pre-pregnancy diagnosis of high blood pressure or diabetes.
Women who had been in remission for at least six months before getting pregnant were considered as having planned pregnancies, while women who had active lupus six months before getting pregnant were considered as having unplanned pregnancies.
The researchers recorded whether the women carried the pregnancies to term or whether the baby was born preterm (before 37 weeks of gestation) and/or underweight; they also assessed if the women had a miscarriage or had to undergo a therapeutic abortion (performed to avoid risks to the mother’s life).
Overall, 300 women had their children, and 38 lost them; 88 babies were born preterm, 68 were born with low weight (13 were from full-term births), and four were born with malformations.
The more robust risk factors for fetal loss were unplanned pregnancies, low levels of member of the complement C3, and high levels of protein in the urine. These were used to construct the model.
“Here, we developed a prediction model with a risk score classification that is simple to use and has predictors that are very easy to obtain clinically,” the researchers said. “Patients can be classified into different risk groups based on the values of these three variables, which may help obstetricians and rheumatologists predict pregnancy outcomes.”
More studies that evaluate a higher number of pregnant SLE patients will help validate the model and increase its sensibility. Researchers also plan to assess other variables, such as the use of different medications.