This study evaluated whether a combined program of supervised Clinical Pilates Exercise and structured Prenatal Education, added to routine antenatal care, reduces perinatal depressive symptoms compared with routine antenatal care alone in nulliparous pregnant women. Secondary aims were to assess effects on pregnancy-related low back pain, labor pain, and obstetric outcomes. Allocation to the two groups was based on participants' availability to attend the program rather than on randomization; the study is therefore a non-randomized (quasi-experimental) controlled study.

This was a prospective, non-randomized, controlled (quasi-experimental) study conducted at a single tertiary women's health center between January 2021 and June 2022. Eighty-five nulliparous women with singleton pregnancies between 16 and 28 weeks of gestation, aged 18-35 years and with a pre-pregnancy body mass index below 30 kg/m2, were enrolled.

Participants were allocated to two parallel groups according to their availability to attend the intervention program. Women who could commit to the scheduled sessions were assigned to the intervention group (n=41) and received a supervised Clinical Pilates Exercise program (two 60-minute sessions per week until 32 weeks of gestation, moderate intensity, Borg 12-14, designed per ACOG recommendations) combined with a structured Prenatal Education program (four weekly sessions). After 32 weeks, exercises were continued at home with modifications. Women unable to attend due to scheduling constraints formed the control group (n=44) and received routine antenatal care only.

Depressive symptoms were assessed with the Edinburgh Postnatal Depression Scale (EPDS) at baseline (16-28 weeks), at 32 weeks of gestation, and at 6 months postpartum. Pregnancy-related low back pain was assessed with the Numeric Pain Rating Scale, labor pain with a Visual Analog Scale (vaginal deliveries), and obstetric outcomes (duration of labor, mode of delivery, gestational age at delivery, birth weight, Apgar scores) were recorded after delivery.

Because allocation was not randomized and significant baseline differences were observed between groups, baseline-adjusted analyses (mixed-effects models, ANCOVA) and propensity-score sensitivity analyses were used. Given the non-randomized design, findings are considered hypothesis-generating. The study was registered retrospectively.

Inclusion Criteria:

• Nulliparous
• Singleton pregnancy
• Gestational age 16-28 weeks at enrollment
• Age 18-35 years
• Pre-pregnancy body mass index < 30 kg/m2

Exclusion Criteria:

• Multiple pregnancy
• Systemic disease, including diabetes mellitus, hypertension, or cardiovascular disorders

De-identified participant data are available in the Zenodo repository.