Statistical Analysis
SPONTANEOUS ABORTION, SECONDARY
The primary analyses compared the primary and secondary outcomes between GPNC and IPNC groups using the ITT approach. The ITT sample included all study participants according to their randomized assignment, regardless of missed visits, crossover between IPNC and GPNC, or transfer out of the practice. In the sensitivity analyses, a mITT approach was used, excluding participants with (1) spontaneous abortion, (2) intrauterine fetal demise, (3) incomplete information on the number of prenatal care visits, and (4) no postrandomization prenatal care visits in their assigned study group. According to our previously published observational study,For the description of baseline characteristics and prognostic factors, continuous variables were described by mean (SD), and categorical variables were described by count (percentage). The missingness of the baseline characteristics and prognostic factors were mainly due to participants’ preference of not answering. The missingness of marital status (516 participants [22.0%]), annual household income (714 participants [30.4%]), and health insurance (270 participants [11.5%]) were greater than 10% and were kept as a separate category during the statistical analysis. Missing data of other variables were lower than 7%, ranging from 2 participants [0.1%] for prepregnancy BMI to 63 participants [6.9%] for GWG. Log binomial models were performed to estimate risk differences (RDs), 95% CIs, and 