Weight Loss Between Pregnancies Associated with Premature Birth

There is plentiful evidence that women who are overweight or obese during pregnancy have a greater risk of health complications associated with their pregnancies than women who are of a healthy bodyweight.

However, what this widespread coverage of maternity weight frequently fails to address is the risks inherent in being underweight. Now a piece of research from the University of Southampton has gone some way to redressing this with the publication of a study detailing how non-overweight women who lose a significant amount of weight between pregnancies have a greater risk of having a premature birth.

The study found that one percent of women with a BMI within the recommended range of 18.5kg and 24.9kg lost a significant amount of bodyweight between pregnancies. There are various reasons why a woman may lose a lot of weight between pregnancies. These include the following:

  • Ill health
  • Stress
  • An eating disorder
  • Dental problems
  • Parasitic infection
  • Malabsorption
  • Medication-related problems
  • Hyperthyroidism
  • Bowel disease
  • Cachexia

The research was led by Dr Alwan from the faculty of medicine at the University of Southampton. Dr Alwan and his team examined the data of 15,000 women’s pregnancies between 2003 and 2018. To be included in the study, the women needed to have experienced at least two pregnancies across the fifteen-year period.

The study found that gaining weight was more common than losing weight, with around 50% of all women gaining weight between their two pregnancies; in contrast, just one in six women lost weight between their two pregnancies.

Interestingly, the women who gained the most weight between pregnancies tended to be from more deprived socio-economic backgrounds, to have lower levels of education, were more likely to be smokers, were less likely to be in employment and were likely to have experienced a more prolonged interpregnancy interval.

The ultimate conclusion of the researchers? The best possible weight for pregnancy is, unsurprisingly, to have the recommended BMI weight of between 18.5kg and 24.9kg from the beginning of a pregnancy.

Dr Nisreen Alwan commented, “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 help mothers maintain a healthy weight in this period.”

Details of the latest study were published in the scientific journal PLOS One, and come shortly after the same team of researchers found evidence that babies born to women who develop significant amounts of weight between pregnancies are more likely to larger and heavier.

What is healthy?

Although knowing your bodyweight and BMI is a useful aid to ensuring that you are a healthy weight for pregnancy, the best way to ensure a healthy pregnancy weight is to eat a balanced and varied diet that includes plenty of fresh and unprocessed food. In fact, sometimes it can be unhelpful to fixate with the numbers, although a number-based approach may work for some women. Everyone’s different; talk to your GP or midwife for more information.