Mediterranean diet or mindfulness during pregnancy reduces by one third the risk of a low birth weight baby

Low birth weight affects up to 10% of pregnancies and stems from fetal growth restriction. Until today, no treatment that could improve this condition is available.

A study published in JAMA led by researchers from BCNatal (SJD Barcelona Children's Hospital and Hospital Clínic-IDIBAPS) and Universitat de Barcelona, with the support of the ”La Caixa” Foundation, has demonstrated for the first time that fetal growth can be improved by maternal lifestyle changes. The study specifically demonstrates a reduction of low birth weight babies up to 29% and 36% by intervening on the mother’s diet and lowering her stress level. 

The study was coordinated by Eduard Gratacós, director of BCNatal and the Fetal and prenatal medicine group at IDIBAPS and CIBERER, Francesca Crovetto (SJD Barcelona Children Hospital) and Fàtima Crispi (Hospital Clínic), from the Maternal-Fetal Medicine and Obstetrics Services of BCNatal and researchers from the same groups. It was conducted in collaboration with the teams of Ramon Estruch, from the Internal Medicine Service at Hospital Clínic, head of the Cardiovascular risk, nutrition and aging group at IDIBAPS and researcher at CIBERON; Eduard Vieta, head of the Psychiatry and Psychology Service at Hospital Clínic, from the Bipolar and depressive disorders group at IDIBAPS and scientific director of CIBERSAM, as well as professionals from the Instituto esMindfulness, directed by Andrés Martín-Asuero. The project also received the support of CEREBRA, CIBERER and AGAUR.  

Low birth weight is associated with birth complications and health problems

Low birth weight babies (birth weight below the 10th centile) account for 10% of all births. Low birth weight reflects growth restriction in fetal life, it is recognised by the World Health Organization as one of the most important causes of perinatal mortality worldwide and it is linked to poorer neurodevelopment in childhood and higher risk of metabolic and cardiovascular health problems in adulthood. No treatment had existed until now that could prevent or improve low birth weight. 

The research team led by Eduard Gratacós has been studying the possible causes and consequences of low birth weight for many years. “We saw that mothers of low birth weight newborns often had a suboptimal diet and high stress levels,” explains Gratacós. This led to the idea of conducting a clinical trial to study whether structured interventions based on Mediterranean diet or stress-reduction could reduce fetal growth restriction and other pregnancy complications.  

IMPACT BCN study: maternal lifestyle intervention

The three-year IMPACT Barcelona study involved more than 1,200 pregnant women at high risk of having a small baby at birth. Pregnant women were randomly divided into three groups: one in which pregnant women had visits with a nutritionist in order to follow a Mediterranean diet, a second group in which they followed a mindfulness programme to reduce stress, and a control group with usual monitoring. A follow-up was then conducted to see how the baby was developing and whether there were any complications during pregnancy and delivery.

The dietary intervention was based on methods used in the PREDIMED study, that demonstrated the benefits of a Mediterranean diet to prevent cardiovascular disease, which was endorsed by the American Heart Association. Pregnant women in this group had a monthly visit with a nutritionist to change their dietary patterns and adapt these to a Mediterranean diet, incorporating more fruit and vegetables, white meat, oily fish, dairy products, whole wheat grains and products high in omega-3 and polyphenols. They were therefore given free extra virgin olive oil and walnuts. “We measured biomarkers in blood and urine related to the intake of walnuts and olive oil in order to assess objectively if they were adhering to this intervention,” explains Francesca Crovetto. 

The stress reduction intervention was based on the Mindfulness-Based Stress Reduction (MBSR) programme developed by University of Massachusetts and adapted to pregnancy by the Barcelona researchers. Groups of 20-25 women were formed to follow the pregnancy-adapted programme for eight weeks. “Questionnaires were completed at the programme’s beginning and end and levels of stress-related hormones, cortisol and cortisone, were measured in order to identify if any stress reduction had occurred,” says Crovetto. 

The study has demonstrated, for the first time, that a Mediterranean diet or mindfulness during pregnancy reduces the percentage of low birth weight and improves complications in pregnancy, such as preeclampsia or perinatal death, when used in a structured, guided manner. “The results were clear: pregnant women in the control group had 21.9% of low birth weight newborns, and this percentage was significantly reduced in the Mediterranean diet (14%) and mindfulness (15.6%) groups,” explains Fàtima Crispi. “We are now designing a multicentre study to apply these results to any pregnant woman, without the need to be at risk of having a low weight baby,” she adds. 

“This is groundbreaking research, as it demonstrates for the first time that a structured lifestyle intervention reduces complications in pregnancy for which no previous treatment had previously demonstrated positive effects,” explains Gratacós.