Preeclampsia and preterm birth are major risks in pregnancy that are characterized by an increased inflammatory response, which is partly explained by microbial stimulation of the innate immune system and generation of pro-inflammatory mediators. Although the use of probiotics might reduce certain complications of pregnancy (here; here), little is known regarding whether timing of probiotic exposure could affect the pathophysiology of pre-eclampsia and premature delivery.
A new prospective cohort study, led by Dr. Verena Sengpiel from the Department of Obstetrics and Gynecology at Sahlgrenska University Hospital in Gothenburg (Sweden), has found that timing of probiotic milk consumption (before or during pregnancy) may influence preeclampsia and preterm delivery.
The study comprised 70,149 mother-infant pairs from the Norwegian Mother and Child Cohort Study (MoBa) -a prospective population-based pregnancy cohort study conducted by the Norwegian Institute of Public Health in 1999-2008. 37,050 nulliparous women were included for preeclampsia analysis and 34,458 women with both iatrogenic and spontaneous preterm delivery (before 37 weeks) were included for the preterm delivery analysis. Women with chronic diseases or pregnancy complications (rheumatoid arthritis, chronic kidney disease, chronic hypertension, chronic heart disease, diabetes mellitus types 1 and 2 and gestational diabetes, immunosuppression, epilepsy, asthma, and serious foetus malformations) were excluded.
At gestational weeks 15 and 30 women answered general questionnaires covering health, lifestyle, medical history and other background factors and at gestational week 22 the researchers administered a food frequency questionnaire. Specifically, questionnaires at 15 weeks (assessing probiotic milk consumption both before pregnancy and during early pregnancy up to around week 17) and 30 weeks (assessing late pregnancy) of pregnancy contained questions about intake of the two available probiotic milks in Norwegian stores (one contained Lactobacillus acidophilus LA-5, Bifidobacterium lactis Bb12 and L. rhamnosus GG and the second one contained L. acidophilus LA-5 and B. lactis Bb12 –both at a dose of 108 probiotic bacteria/mL).
Main outcome measures consisted of Odds Ratio (OR) -representing the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure- for preeclampsia and preterm delivery according to consumption of probiotic milk before pregnancy, and during early and late pregnancy.
Based on the questionnaire data, 6,502 women (23%) said they had consumed probiotic milk products before pregnancy. Besides this, 11,221 women (37%) had done so during early pregnancy and 12,784 women (32%) had done so during late pregnancy.
Intake of probiotic milk products was more common among those women who were older, primiparous, of normal weight, and had higher educational levels and family income.
It is important to take into account that although the questionnaires were filled in before delivery to avoid confounding by retrospective response, the self-reported nature of the dietary data for these pregnant women is the main limitation of this study.
Probiotic milk intake during late pregnancy was significantly associated with a 20% lower risk of preeclampsia. When severity of preeclampsia was added into the equation, the association between probiotic milk exposure and the risk of preeclampsia was significantly only for those whose condition was severe. Besides this, probiotic intake during early pregnancy was significantly associated with a lower risk of preterm delivery. In a subgroup analysis, a significant association was found for probiotic consumption during early pregnancy and lower risk of late preterm delivery. When preterm delivery was divided into spontaneous and iatrogenic preterm delivery, a correlation was only found between probiotic consumption during early pregnancy and lower risk of spontaneous preterm delivery. No significant dose response effect was found for both conditions.
In conclusion, this large-scale epidemiological study has found that timing of probiotic milk consumption during pregnancy is correlated with the incidence of preeclampsia and preterm delivery. Further research based on randomised controlled trials are needed to establish a causal relationship between probiotic consumption and reduced risk of these adverse pregnancy outcomes.
Nordqvist M, Jacobsson B, Brantsæter AL, et al. Timing of probiotic milk consumption during pregnancy and effects on the incidence of preeclampsia and preterm delivery: a prospective observational cohort study in Norway. BMJ Open. 2018; 8(1):e018021. doi: 10.1136/bmjopen-2017-018021.