A package of care for all pregnant women within eight scheduled antenatal care contacts is recommended by WHO. Some interventions for reducing and managing the outcomes for small vulnerable newborns (SVNs) exist within the WHO package and need to be more fully implemented, but additional effective measures are needed. We summarise evidence-based antenatal and intrapartum interventions (up to and including clamping the umbilical cord) to prevent vulnerable births or improve outcomes, informed by systematic reviews. We estimate, using the Lives Saved Tool, that eight proven preventive interventions (multiple micronutrient supplementation, balanced protein and energy supplementation, low-dose aspirin, progesterone provided vaginally, education for smoking cessation, malaria prevention, treatment of asymptomatic bacteriuria, and treatment of syphilis), if fully implemented in 81 low-income and middle-income countries, could prevent 5·202 million SVN births (sensitivity bounds 2·398–7·903) and 0·566 million stillbirths (0·208–0·754) per year. These interventions, along with two that can reduce the complications of preterm (<37 weeks’ gestation) births (antenatal corticosteroids and delayed cord clamping), could avert 0·476 million neonatal deaths (0·181–0·676) per year. If further research substantiates the preventive effect of three additional interventions (supplementation with omega-3 fatty acids, calcium, and zinc) on SVN births, about 8·369 million SVN births (2·398–13·857) and 0·652 million neonatal deaths (0·181–0·917) could be avoided per year. Scaling up the eight proven interventions and two intrapartum interventions would cost about US$1·1 billion in 2030 and the potential interventions would cost an additional $3·0 billion. Implementation of antenatal care recommendations is urgent and should include all interventions that have proven effects on SVN babies, within the context of access to family planning services and addressing social determinants of health. Attaining high effective coverage with these interventions will be necessary to achieve global targets for the reduction of low birthweight births and neonatal mortality, and long-term benefits on growth and human capital.