Probiotics May Not Reduce the Risk of Gestational Diabetes in Some Women

Women who are pregnant, or who are planning to become pregnant, are no stranger to discussions about gestational diabetes.  Preventing diabetes during pregnancy, testing for it, and planning for treatment if necessary are part of most routine prenatal care plans.

Many women take vitamins and supplements to help reduce the risk of gestational diabetes and other complications of pregnancy.  Probiotics, for example, are commonly taken as a means of promoting healthy bacteria and preventing complications, including gestational diabetes.  However, a new study published in Diabetes Care suggests that in some women, Probiotics are not beneficial in reducing the risk of gestational diabetes.

gestational diabetes

Study: Probiotics Not Beneficial in Reducing the Risk of Gestational Diabetes

The study titled “Study of Probiotics in Gestation” (SPRING), analyzed whether probiotics administered during the second trimester were beneficial in preventing gestational diabetes among overweight or obese women.  The study was prospective, double-blind, and used a randomized controlled trial with probiotics versus a placebo.  The participants in the study consisted of women:

  • 18 and older
  • Pregnant with a single fetus
  • 20 weeks gestation or less
  • Body mass index (BMI) of 25 or higher

Participants were all screened for plasma glucose levels prior to initiating the study.  Participants were then randomly assigned to a probiotics or placebo.  The probiotics used included Lactobacillus rhamnosus and Bifidobacterium animalis subspecies lactis. 

The outcome measured was the frequency of gestational diabetes by 28 weeks gestation.  Secondary maternal outcomes considered included weight gain, preeclampsia, requirement of cesarean delivery, and the gestational age at the time of delivery.  Secondary fetal outcomes considered included birth weight, prematurity, jaundice, hypoglycemia, congenital factors, small for gestational age (SGA), birth injury, and stillbirth.

Study Results

At 28 weeks gestation, study participants were re-screened to test their plasma glucose levels.  The results indicated the following:

  • The rate of gestational diabetes among the probiotic group was 18.4 percent (38 out of 207 participants).
  • The rate of gestational diabetes among the placebo group was 12.3 percent (25 out of 204 participants).

This means that fasting glucose levels were higher in participants receiving probiotics compared with those receiving the placebo.  In terms of secondary outcomes, the results indicated:

  • The rate of preeclampsia among the probiotic group was 9.2 percent.
  • The rate of preeclampsia among the placebo group was 4.9 percent.
  • Excessive weight gain was reported in 32.5 percent of the probiotic group.
  • Excessive weight gain was reported in 46 percent of the placebo group.
  • Neonatal outcomes did not differ between the two groups, with the exception of SGA, which was reported to be present in 2.4 percent of the probiotic group, and in 6.5 percent of the placebo group.

Based on these results, researchers concluded that administering probiotics during the second trimester of pregnancy does not prevent gestational diabetes or improve secondary outcomes in women who are overweight or obese.

What Women Should Know about Gestational Diabetes

According to the Centers for Disease Control and Prevention (CDC), around 9.2 percent of pregnant women develop gestational diabetes.  Gestational diabetes is a complication of pregnancy that usually develops in the second trimester, around 24 weeks gestation.  This is a complication that can develop in women who have no history of diabetes prior to conceiving.  Most women find that gestational diabetes resolves following delivery.

Type 1 and Type 2 diabetes develop when the body can no longer respond to insulin effectively.  That means that the body does not absorb glucose properly, causing it to build up in the bloodstream.  Many people develop diabetes due to genetics, obesity, or other health issues.  Gestational diabetes, however, is caused by hormonal changes that only occur during pregnancy.

During pregnancy, the hormones that are responsible for breaking down insulin or increasing blood glucose levels tend to override hormones responsible for lowering blood glucose levels.  The responsible hormones include:

  • Estrogen
  • Progesterone
  • Cortisol
  • Growth hormones
  • Human placental lactogen (A placental hormone responsible for breaking down fat in the mother and transferring it to energy for the fetus).
  • Placental insulinase (Another placental hormone responsible for inactivating insulin).

Risk Factors

The study discussed above focused on women who are overweight or obese, which are two of the most common risk factors for developing gestational diabetes.  There are, however, many other risk factors that women should be aware of.  These include:

  • History of being overweight or obese
  • Gaining excessive weight during pregnancy
  • Being over 25 at the time of pregnancy
  • Women of African, Asian, American Indian, Hispanic, or Pacific Islander descent have higher rates of gestational diabetes.
  • Prediabetes (blood glucose is elevated but not enough to be diagnosed as diabetes)
  • History of gestational diabetes
  • Family history of Type 2 diabetes
  • Hormone disorders (example includes polycystic ovary syndrome (PCOS))
  • Previous pregnancy resulting in a child at least nine pounds
  • History of birth defects among children
  • History of unexplained stillbirth or miscarriage

How Gestational Diabetes Affects Babies

Because gestational diabetes develops in the second trimester after the majority of the fetus’s body has been formed, there are less risks to the baby than among mothers who already have been diagnosed with Type 1 or Type 2 diabetes.  Gestational diabetes can, however, affect your baby if it is not properly diagnosed or treated.  The most common risk for the baby is macrosomia, or an infant who is significantly larger than average.

If not properly diagnosed and treated, gestational diabetes can lead to excessive amounts of glucose being passed to the fetus.  Insulin does not cross through the placenta, but glucose does.  So the baby’s pancreas may work in overtime to produce enough insulin to regulate blood glucose levels.  Glucose that cannot be properly absorbed is stored as fat in the baby, which increases weight, causing macrosomia.

Babies who develop macrosomia are more likely to experience:

Mothers of babies with macrosomia also face some risks unique to a larger-than-average baby.  These risks include:

Can Gestational Diabetes be Prevented?

There is no guaranteed way of preventing gestational diabetes.  However, you can take measures to reduce your risk of developing this and other complications of pregnancy.  The steps you can take to reduce your risk of developing gestational diabetes include:

Eat Wisely

Eating a healthy diet is important at any stage of life, but is even more important during pregnancy. Eating wisely is one of the best ways to reduce the risk of gestational diabetes.  Pay attention to what you eat, when you eat, and how much you eat.  If you are concerned about your diet, talk to your doctor about scheduling a consultation with a registered dietician (RD) or a certified diabetes educator (CDE).


Again, exercising is an important part of life for anyone at any stage of life. During pregnancy, your body is changing in unimaginable ways on the inside.  Your body is feeding and providing energy to the life inside you, which means your own body is producing more of substances like glucose to compensate.  By exercising during pregnancy, you can help offset the extra glucose your body is producing and reduce the risk of becoming insulin resistant.


If you already have diabetes or are considered at a high risk for developing it, then your doctor may decide to give your body a bit of help in the form of insulin or other medications that help regulate blood glucose levels.


Another good way to reduce the risk of complications and manage complications that do arise is by planning in advance. Talk to your doctor about any health concerns or medical history that could help you plan for your upcoming delivery.

Taking steps to reduce your risk of developing gestational diabetes is important.  So is talking to your doctor about any concerns you have, or questions that come up during your pregnancy.  Being proactive and an active participant in your own health can help reduce the risk of complications, including gestational diabetes or birth injuries.

Meagan Cline

Written By Meagan Cline

Meagan Cline is a professional legal researcher and writer. She lends her expertise to the team at Birth Injury Guide to provide up-to-date and relevant content that clients can count on.