Study design and participants
renal dysfunction, diabetes
VITAMIN D DEFICIENCY, CHRONIC DISEASES, SECONDARY, VITAMIN D DEFICIENCY, -20, LIVER DISEASES, HYPERTENSION, DIABETES
This study presents a secondary analysis of data collected from the Khuzestan Vitamin D Deficiency Screening Program in Pregnancy, which was a stratified randomized controlled field trial. The study protocol and procedures have been previously publishedThis study was conducted in two phases. The first phase involved a population-based cross-sectional study that recruited 1,600 and 900 first-trimester pregnant women from health centers in Masjed-Soleyman and Shushtar, respectively. The sampling method used was stratified multistage cluster sampling with probability proportional to size (PPS). Inclusion criteria include age range 18–40 years, gestational age < 14 weeks, singleton pregnancy, not consuming multivitamins containing 400 IU/d of D3, and no previous history of chronic diseases. Participants consuming multivitamins containing more than 400 international units (IU) per day of vitamin D3 and anticonvulsants and those with a history of chronic diseases like diabetes, hypertension, renal dysfunction, liver diseases, and complicated medical or obstetrical history were excluded from the study. The study data was collected from 1800 first-trimester pregnant women referred to health centers in Masjed-Soleyman (intervention) and Shushtar (control), from whom fasting blood samples were collected. Serum samples of participants from Shushtar were stored and kept frozen at -80° C until further assays at the end of the study, according to the original study protocol. The vitamin D status of participants from Masjed-Soleyman was measured immediately, and those found to have vitamin D deficiency were randomly assigned to a treatment regimen consisting of vitamin D3 supplementation until delivery. During the second phase of the study, based on 25(OH)D levels, mothers were divided into severe deficient (< 10 ng/ml), moderate deficient (10-20 ng/ml), and normal status (> 20 ng/ml) (6). A total of 800 pregnant women with vitamin D deficiency (defined as serum concentrations of 25(OH)D < 20 ng/ml) from Masjed-Soleyman were included in the intervention group and received vitamin D supplementation according to the assigned protocol. Participants were randomized into groups of four using a computer-generated list. The physicians involved in the study were not informed about which group each woman was placed in, but the midwife who was not involved in any phase of the study knew. It was not possible to hide the treatment allocation from healthcare workers, but those who assessed pregnancy outcomes were unaware of the treatment allocation. The remaining women with vitamin D deficiency were referred to specialists for further treatment. Participants from Shushtar served as the control group and did not receive any vitamin D supplementation. Women with severe and moderate vitamin D deficiency from Masjed-Soleyman were randomly allocated to one of four treatment modalities: A1 (treatment with 50,000 IU of oral vitamin D3 weekly for a total duration of 12 weeks), A2 (treatment with 50,000 IU of oral vitamin D3 weekly for a total duration of 12 weeks and then on a monthly maintenance dose of 50,000 IU vitamin D3 until delivery), A3 (intramuscular administration of 300,000 IU vitD3; 2 doses for 6 weeks), and A4 (Intramuscular administration of 300,000 IU vitamin D3; 2 doses for 6 weeks and then on a monthly maintenance dose of 50,000 IU vitamin D3 until delivery). Women with moderate vitamin D deficiency were assigned to one of four study groups: B1 (treatment with 50,000 IU oral vitamin D3 weekly for a total duration of 6 weeks), B2 (treatment with 50,000 IU oral vitamin D3 weekly for a total duration of 6 weeks and then on a monthly maintenance dose of 50,000 IU vitamin D3 until delivery), B3 (a single dose of intramuscular administration of 300,000 IU vitamin D3), and B4 (a single dose of Intramuscular administration of 300,000 IU vitamin D3 and then on a monthly maintenance dose of 50,000 IU vitamin D3 until delivery). Serum levels of 25 (OH)D of all participants (from both cities) were measured at delivery. All participants (intervention and control groups) received routine prenatal care and followed till delivery.For this analysis, elective and repeat cesarean section cases, those without reliable data about the type of cesarean section (n = 143), IUFD (n = 2), and incomplete data on predictors (n = 6) were excluded. As a result, a total of 1488 pregnant women were included in the analysis (Fig. The study flow-diagram.