Maternal Serum BLyS Levels Throughout Pregnancy

The investigators performed a prospective observational study of pregnant women presenting for prenatal care at Los Angeles County+University of Southern California Obstetrics clinics. Subjects were recruited from October 2011 through June 2013. Pregnant women were recruited at the time of their first prenatal visit. Women under the age of 18 and women carrying a fetus with a known major congenital anomaly were excluded. A control group of premenopausal nonpregnant (NP) women without known medical or rheumatic illnesses was recruited from the Los Angeles County+University of Southern California Gynecology outpatient clinics. Informed consent was obtained from each study participant before enrollment. Approval for this study was obtained from the Los Angeles County+University of Southern California Institutional Review Board.

A participant was classified as having gestational hypertension if the participant had ≥2 episodes of new-onset HTN (systolic blood pressure >140 mm Hg or diastolic blood pressure >90 mm Hg) after 20 weeks of pregnancy. PE was defined as gestational hypertension that was accompanied by proteinuria of at least 300 mg in a 24-hour urine collection or a protein/creatinine ratio ≥0.3. HELLP syndrome was diagnosed when a woman had laboratory evidence of hemolysis, a platelet count <100,000/μL, and serum levels of aspartate aminotransferase and alanine aminotransferase that were greater than or equal to twice normal values. Superimposed preeclampsia was diagnosed in a participant with CHTN when the participant experienced an acute exacerbation of hypertension after 20 weeks of gestation. In a participant without preexisting proteinuria, new-onset proteinuria was also required for the diagnosis.

Patient characteristics were obtained through patient interviews and medical chart review. Maternal venous blood was collected by venipuncture at least once per trimester, on admission for delivery, and postpartum. The first trimester was defined as <14 gestational weeks, the second trimester as 14 0/7 to 27 6/7 gestational weeks, and the third trimester as 28 0/7 gestational weeks to delivery. Postpartum samples were collected before hospital discharge after delivery.

Blood samples were collected in sterile tubes without additives and refrigerated until processing. Sera were routinely isolated from the clotted blood samples within 12 to 24 hours and were aliquotted and stored at -80°C. Serum BAFF levels were measured in a blinded fashion using a sandwich ELISA.

Chi-squared or Fisher exact testing was used for categorical variables, and Kruskal-Wallis or signed-ranks testing was used for all continuous variables. All tests were 2-sided, with a P value <0.05 considered statistically significant. Means are expressed as ± the SD. Medians are presented for data not normally distributed.

Inclusion criteria

• Adult woman

Exclusion criteria

• Unable to give informed consent