Optimizing skeletal health in early life has potential effects on bone health later in childhood and in adulthood. We aimed to evaluate the existing evidence that maternal exposures during pregnancy have an impact on the subsequent bone health among offspring in young adults aged between 16 and 30 years. The protocol is registered in the International Prospective Register of Systematic Reviews (PROSPERO) (ID: CRD42019126890). The search was conducted up to 2 April 2019. We included seven observational prospective cohort studies that examined the association between maternal dietary factors, vitamin D concentration, age, preeclampsia, and smoking with any bone indices among offspring. The results indicated that high concentrations of maternal vitamin D; low fat intake; and high intakes of calcium, phosphorus, and magnesium may increase the bone mineral density in offspring at age 16. Evidence also suggests that the offspring of younger mothers may have a higher peak bone mass. It remains inconclusive whether there is an influence of preeclampsia or maternal smoking on bone health among young adults. Our assessment of internal validity warrants a cautious interpretation of these results, as all of the included studies were judged to have serious risks of bias. High-quality studies assessing whether prenatal prognostic factors are associated with bone health in young adults are needed.