Obesity is rising in the obstetric population, yet there is an absence of services and guidance for the management of maternal obesity. This systematic review aimed to investigate relationships between obesity and impact on obstetric care. Literature was systematically searched for cohort studies of pregnant women with anthropometric measurements recorded within 16-weeks gestation, followed up for the term of the pregnancy, with at least one obese and one comparison group. Two researchers independently data-extracted and quality-assessed each included study. Outcome measures were those that directly or indirectly impacted on maternity resources. Primary outcomes included instrumental delivery, caesarean delivery, duration of hospital stay, neonatal intensive care, neonatal trauma, haemorrhage, infection and 3rd/4th degree tears. Meta-analysis shows a significant relationship between obesity and increased odds of caesarean and instrumental deliveries, haemorrhage, infection, longer duration of hospital stay and increased neonatal intensive care requirement. Maternal obesity significantly contributes to a poorer prognosis for mother and baby during delivery and in the immediate post-partum period. National clinical guidelines for management of obese pregnant women, and public health interventions to help safeguard the health of mothers and their babies are urgently required.