Background: Inadequate nutritional status during pregnancy can lead to adverse birth outcomes but this is more so for pregnant adolescents as they require nutrients to meet their needs for growth and that of the foetus. The study examined the relationship between nutritional status and birth outcomes among Ghanaian teenagers in rural and urban districts of the Ashanti Region, Ghana.Methods In this prospective cohort study, 416 pregnant teenagers recruited at hospitals/health centres during antenatal care were followed until delivery. Data on weight, height (for body mass index), mid-upper arm circumference (MUAC), and nutrients intake using a repeated 24-hour dietary recall were determined. Blood samples were also taken and analysed for haemoglobin (Hb), serum levels of ferritin, prealbumin, vitamin A, total antioxidant capacity (TAC), C-reactive protein (CRP), and zinc protoporphyrin (ZPP). Birth weight, gestational age at birth, type of delivery, and outcome of delivery were collected as each teenager gave birth. Data were analysed using Chi-square (Fisher’s exact) analysis, t-test, two-way ANOVA and multiple linear regression. Results: 15.9% had low birth weight, 12.5% had preterm birth, 11.5% had a postpartum haemorrhage, and 3.1% neonatal deaths. Majority of the participants had inadequate intakes of energy (81.4%), protein (77.2%), vitamins A (97.1%) and E (97.7%), calcium (99.8%), iron (97.6%), folate (93.0%), zinc (83.7%), riboflavin (88.4%), thiamin (74.4%), and fiber (74.4%) intakes. Anaemia and wasting prevalence were 57.1% and 27.8%. Between-subject effects determined using Generalized Linear Modelling indicated MUAC (p=0.058), and gestational age at delivery (p=0.023) significantly affected birth weight. A multiple linear regression analysis indicated MUAC (β=0.283, p=0.002), BMI (β=0.221, p=0.015), gestational age (β=0.285, p<0.001), and ZPP (β=0.131, p=0.057) were significantly associated with birth weight (F(23, 223), P=0.008, R2=1.941).Conclusions: Inadequate nutrients intake, anaemia, and LBW were found in these pregnant teenagers. Maternal MUAC, gestational age, and serum ZPP were associated with birth weight. Interventions for improving the nutritional status of teenagers before and during pregnancy are urgently needed to reduce the risk of adverse birth outcomes.