Twin pregnancy is a high-risk obstetric condition associated with prematurity and selective intrauterine growth restriction. Although management mainly occurs in specialized care, Primary Health Care is strategic for early risk identification, prenatal follow-up, and care coordination, impacting maternal and perinatal outcomes.This report describes the care of a 33-year-old woman, G5P1A3, with a dichorionic twin pregnancy in a bicornuate uterus, followed in prenatal care and timely referred to high-risk services. One fetus developed severe selective intrauterine growth restriction, with estimated fetal weight below the 10th percentile and progressive Doppler abnormalities, including absent and reversed end-diastolic flow, associated with fetal distress. Coordination between Primary Health Care, specialized services, and the hospital team enabled intensified surveillance and shared decision-making regarding pregnancy interruption. Delivery occurred by cesarean section at 34 weeks and 2 days, with immediate neonatal support and multidisciplinary follow-up.This case demonstrates that Primary Health Care acts beyond care coordination, integrating with specialized services from early prenatal follow-up. Its role in prevention, early risk detection, and longitudinal monitoring ensured continuity of care and was essential for comprehensive maternal and child health care, despite obstetric resolution in specialized settings.Early identification of risk factors during prenatal care, combined with timely referral and effective articulation between Primary Health Care and specialized services, supports appropriate clinical decision-making and the prevention of severe perinatal outcomes. Strengthening PHC as an active component of shared care improves the quality of maternal and child health services.Selective intrauterine growth restriction in dichorionic twin pregnancies is associated with placental abnormalities and may be aggravated by uterine malformations. In this case, a bicornuate uterus likely contributed to placental insufficiency in one fetus, with progressive Doppler abnormalities supporting timely pregnancy interruption. Although management occurred in specialized care, Primary Health Care was fundamental for early risk recognition, referral, and longitudinal follow-up, positively impacting perinatal outcomes.Integrated action between Primary Health Care and specialized services is essential for the safe management of twin pregnancies complicated by selective intrauterine growth restriction. Through surveillance, shared care, and continuity of assistance, PHC plays a decisive role in improving perinatal outcomes, even in highly complex obstetric settings.