The study, published in the journal Maternal and Child Health Journal, showed that if these factors were modified, it could reduce the risk of premature births.
"The highest risks for premature birth were in women who were underweight, had poor weight gain during pregnancy, or short periods of time between pregnancies. Excessive weight gain in obese women also increased the risk," said Emily DeFranco, Associate Professor at the University of Cincinnati.
DeFranco and her colleagues conducted the study from birth records of nearly 4,00,000 people. Potentially modifiable risk factors for preterm birth were present in more than 90 per cent of women in the study.
Fewer than half of women begin pregnancy with a normal weight, and only 32 per cent achieve the recommended pregnancy weight gain.
"Attention should be paid to educational interventions on the importance of birth spacing, achieving an optimal pre-pregnancy weight, and ensuring adequate nutrition and weight gain during pregnancy. Improvements in these modifiable risk factors could have significant influence on premature birth and infant mortality worldwide," DeFranco added.