Women who lose "significant weight" between their first and second pregnancies could have a greater risk of premature birth, according to new research carried out by scientists at the University of Southampton.
They found the increased risk affected mothers who were not overweight.
Dr Alwan's team studied data from 2003 to 2018 of 15,000 women who received antenatal care and lived in Southampton and surrounding parts of Hampshire during at least two of their pregnancies.
"The period between pregnancies is a key window of opportunity to improve health given the close contact families have with health and care professionals, but there has been little research into effective ways to support mothers maintain a healthy weight in this period.
The findings, published in the scientific journal PLOS One, follow another study by the same research team which showed a higher proportion of babies born to women who gained significant weight between pregnancies were too large at birth compared to women who lost weight or remained at a stable weight between pregnancies.
The university spokesman explained that women who gained a significant amount of weight by the start of their second pregnancy were more likely to be smokers, unemployed, with lower educational attainment and to have a longer interpregnancy interval, compared with those who maintained a stable weight between pregnancies.
The study also found overweight women who lost weight after a large-for-gestational-age birth (LGA) in their first pregnancy were less likely to have another large baby in their second pregnancy.
LGA birth carries increased risk for an induced delivery or Caesarean section and obesity for the child later in life.