The team led by Joanna Nieczuja-Dwojacka, PhD, from the Cardinal Stefan Wyszyński University in Warsaw also showed that overweight and obese women gain more weight during pregnancy than international standards assume, despite the fact that they are the ones who are advised to be most careful in this regard. The researchers also noticed that pregnant first-time mothers gain more weight than women having another child, and body weight increases with the number of pregnancies - in subsequent pregnancies it rarely returns to the initial level.

Nieczuja-Dwojacka reminds that more and more studies show that the weight a woman has when she enters pregnancy and how much weight she gains during pregnancy can have very specific and far-reaching consequences - for both the mother and the newborn. However, too little is being said about it, and many women are still unaware of these facts.

'It is worth educating them on this issue and talking to them at the stage of planning a pregnancy, because it is something that can be modified in many cases', the researcher emphasises.

After analysing data collected from 2,878 women aged 16 to 46, who gave birth at the Saint Sophia Hospital in Warsaw and the John Paul II Provincial Hospital in Krosno, the researchers determined that both a high BMI before pregnancy and excessive weight gain during pregnancy significantly increased the risk of many complications and problems.

A higher BMI before pregnancy was associated, for example, with a higher risk of gestational diabetes, hypertension, delivery by caesarean section, and with a higher birth weight of the newborn (macrosomia). It also made natural breastfeeding difficult and resulted in lower Apgar scores. Importantly, some of these problems occurred in women with a BMI of 25, i.e. overweight, not obese.

Nieczuja-Dwojacka explains that all of these complications may have further health consequences, even in the long term. For example, high birth weight may increase the risk of perinatal injuries (such as episiotomy), difficulties with breastfeeding may weaken the newborn's immunity, and metabolic disorders in the mother may worsen in subsequent pregnancies. The researcher also mentions that macrosomia increases the risk of overweight and obesity in later stages of children's development.

In turn, excessive weight gain during pregnancy (i.e. greater than recommended by the Institute of Medicine) increased the risk of macrosomia, perinatal complications and caesarean section.

According to Nieczuja-Dwojacka, it is also worth emphasizing that the average values of women's body mass and BMI increase with each subsequent pregnancy. 'In other words: each time during pregnancy, the weight increases and after delivery this excess does not decrease completely. Consequently, women enter the next pregnancy with a higher weight, and therefore a greater health burden', she says.

The research team also showed that it was overweight and obese women who gained the most during pregnancy. 'The recommended weight gain during pregnancy is different for women who are underweight, women with a normal body weight, and for overweight and obese women. We noticed that women who were overweight and obese gained more than those with a normal body weight. So the adverse effect was even greater', she explains.

That is why, in her opinion, it is so important to build awareness of the need to regulate body weight among women who plan to become mothers. 'It is not about restrictive diets or backbreaking workouts, but about a wisely planned, balanced diet and moderate physical activity, such as walking. Such a lifestyle change can be of great importance not only for the health of the mother, but also her future child', the scientist emphasises.

The authors of the study want the results of their work to contribute to this. That is why, in cooperation with the hospital in Krosno, they are preparing educational materials for women planning a pregnancy. 'This knowledge can really help. We show that it is worth preparing for this period and that too high a body weight is not only a cosmetic problem. It is an important risk factor that can affect the course of labour and the health of the foetus and child', the researcher emphasises.

She adds that the harmful myth that you can eat as much as you want during pregnancy and you should not do sports is still deeply rooted in society. Meanwhile, today's medical knowledge increasingly emphasises the importance of not only conscious nutrition, but also regular physical activity, adapted to the health of the pregnant woman. 'It's not about gaining a black belt in karate, but about movement - walking, swimming, yoga. Anything that will help keep your body in shape and is adapted to the physical condition of the body', Nieczuja-Dwojacka concludes.

The publication about the study was published in Scientific Reports (https://doi.org/10.1038/s41598-025-91879-z).

PAP - Science in Poland, Katarzyna Czechowicz (PAP)

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