The circumstances surrounding sexual debut influence subsequent sexual and reproductive outcomes. We analysed longitudinal data from 397 women who participated in the Cebu Longitudinal Health and Nutrition Survey in Cebu, Philippines, to examine associations between unwanted first sex and number of pregnancies, unintended pregnancy, and use of modern contraception. 72% of women reported unwanted first sex. Women whose first sex was unwanted had increased odds of unintended pregnancy compared to women whose first sex was wanted (aOR = 2.2, 95% CI 1.3, 3.6). Nationally representative surveys should include culturally relevant questions about sexual debut to inform public health programmes aimed at improving sexual/reproductive health.