Scientists in Iceland followed hundreds of children from birth to age 5, collecting samples to study how their gut bacteria develop. They discovered that children’s gut bacteria follow a similar pattern to kids in other countries, but with some unique differences. Interestingly, mothers who had gestational diabetes during pregnancy had different bacteria in their guts, and this difference affected their children’s bacteria too—especially by age 5. This long-term study shows that what happens during pregnancy and early childhood can have lasting effects on the bacteria living in our digestive system.

The Quick Take

  • What they studied: How the bacteria in children’s stomachs and intestines develop from birth to age 5, and whether the mother’s health during pregnancy affects the baby’s bacteria.
  • Who participated: 328 Icelandic children with samples collected from before they started eating solid foods up to age 5, plus 214 of their mothers. Samples were taken multiple times over the years.
  • Key finding: Children’s gut bacteria developed normally, but mothers who had gestational diabetes (high blood sugar during pregnancy) had different bacteria. By age 5, this maternal condition explained about 2.5% of the differences in their children’s gut bacteria.
  • What it means for you: If you’re pregnant or planning to be, managing blood sugar levels may help shape your baby’s digestive health in ways that last for years. However, this is just one piece of the puzzle—many other factors also influence children’s gut bacteria.

The Research Details

Researchers collected poop samples from Icelandic mothers and their children at different time points. They started collecting from children before they ate solid foods and continued until age 5. Mothers provided samples after giving birth. Using special lab techniques, scientists identified which bacteria were present in each sample and studied how the bacterial communities changed over time.

The team used a method called 16S rRNA gene sequencing, which is like taking a fingerprint of all the bacteria in a sample. This allowed them to see which types of bacteria were present and in what amounts. They also predicted what jobs these bacteria might be doing in the body based on their genetic makeup.

This approach is important because it captures the real-world development of gut bacteria in a specific population (Icelandic children) over a long period. By collecting samples at multiple time points, researchers could see how bacteria change as children grow, rather than just taking a snapshot at one moment. Including mothers’ samples helped researchers understand whether and how maternal health affects children’s bacteria.

This study has several strengths: it followed children for 5 years (much longer than many studies), included a large number of participants, and collected multiple samples from each child. The researchers used standardized lab techniques to identify bacteria. However, the study only included Icelandic families, so results may not apply equally to all populations. The study is observational, meaning researchers watched what happened naturally rather than randomly assigning people to different treatments, so we can’t prove that maternal diabetes directly causes changes in children’s bacteria.

What the Results Show

Icelandic children’s gut bacteria developed in patterns similar to what scientists have seen in other countries. However, at age 1, these children had notably higher amounts of a bacteria called Blautia compared to children in other studies. This was an interesting difference that researchers want to understand better.

At age 5, children had more types of bacteria than their mothers did, but their bacteria were less diverse overall (meaning they had fewer different kinds). This suggests that while children’s bacteria are still developing and changing, they haven’t reached the same balance as adult bacteria.

The study found that samples containing archaea (a different type of microorganism) had more diverse bacteria than samples without archaea. This was true for both mothers and children at ages 2 and 5. Archaea appear to be associated with healthier, more balanced bacterial communities.

Mothers who had gestational diabetes during pregnancy showed important differences. They had higher amounts of Blautia bacteria but lower overall diversity in their bacterial communities. More importantly, this maternal condition affected their children’s bacteria too. The effect wasn’t obvious at birth or in early childhood, but by age 5, the connection became clear. Maternal gestational diabetes explained about 2.5% of the differences in children’s gut bacteria at age 5—a small but measurable effect.

The overall pattern of how Icelandic children’s bacteria develop matches what other researchers have found in different countries, which is reassuring. However, the higher amount of Blautia at age 1 is different from what’s been reported in other populations, suggesting that diet, lifestyle, or genetics specific to Iceland may play a role. The finding about archaea and bacterial diversity is new and adds to our understanding of what makes a healthy gut bacterial community.

This study only included families from Iceland, so the results may not apply to all populations around the world. The researchers couldn’t prove that maternal gestational diabetes directly causes changes in children’s bacteria—they only showed that the two are connected. The study is observational, meaning researchers watched what naturally happened rather than testing a specific treatment. Additionally, the effect of maternal gestational diabetes on children’s bacteria was small (2.5%), meaning many other factors also influence how children’s bacteria develop.

The Bottom Line

Pregnant women should work with their healthcare providers to manage blood sugar levels and maintain overall health, as this may influence their baby’s long-term digestive health. However, this is one of many factors affecting children’s health. Parents should also focus on other known important factors like breastfeeding, introducing diverse foods, and avoiding unnecessary antibiotics. These findings are interesting but not yet strong enough to change standard medical advice—more research is needed. (Confidence level: Moderate)

Pregnant women, especially those at risk for gestational diabetes, should be aware of this research. Parents of young children may find it interesting to understand how early life experiences shape their child’s bacteria. Healthcare providers caring for pregnant women and infants should consider these findings as part of the bigger picture of maternal and child health. People interested in how our bodies work and develop should find this research fascinating.

Changes in gut bacteria happen gradually over years, not days or weeks. If a mother manages her blood sugar during pregnancy, the effects on her child’s bacteria would likely develop over months and years, with more noticeable differences appearing by age 5 or later. Don’t expect immediate changes—think of this as a long-term investment in health.

Want to Apply This Research?

  • For pregnant women: Track blood sugar levels if at risk for gestational diabetes, along with dietary intake and exercise. For parents: Monitor digestive health markers in children (like regularity and comfort) and note any changes in diet or health status. Record these observations monthly to see patterns over time.
  • Pregnant women should work with healthcare providers on blood sugar management through diet and exercise. Parents can support healthy gut bacteria development by breastfeeding if possible, introducing diverse foods when appropriate, and minimizing unnecessary antibiotics. Track these behaviors in the app to maintain consistency.
  • Create a long-term health profile that tracks maternal health during pregnancy and child digestive health markers over years. Set reminders for regular check-ins with healthcare providers. Use the app to document dietary changes, health events, and any digestive concerns. Review trends annually to see how early-life factors correlate with current health status.

This research presents interesting findings about how gut bacteria develop in Icelandic children and how maternal gestational diabetes may influence this development. However, this is observational research and does not prove cause-and-effect relationships. The findings are specific to an Icelandic population and may not apply equally to all groups. If you are pregnant, planning pregnancy, or concerned about your child’s digestive health, consult with your healthcare provider. Do not make medical decisions based solely on this research. This information is for educational purposes and should not replace professional medical advice.