Researchers discovered that mothers who are overweight before getting pregnant may be more likely to have babies born with low vitamin K levels. Vitamin K is important because it helps blood clot properly, and babies without enough of it can have serious bleeding problems. Scientists studied 192 babies born at a hospital and found that babies whose mothers had higher weights before pregnancy were nearly four times more likely to have vitamin K deficiency at birth. This finding suggests doctors should pay special attention to vitamin K levels in babies born to mothers who were overweight before pregnancy.

The Quick Take

  • What they studied: Whether a mother’s weight before pregnancy affects how much vitamin K her baby has when born
  • Who participated: 192 newborn babies (64 with low vitamin K and 128 with normal vitamin K levels) born at one hospital between 2018 and 2023, matched by age and sex
  • Key finding: Babies born to mothers who were overweight before pregnancy were about 4 times more likely to have low vitamin K at birth compared to babies of mothers with normal weight
  • What it means for you: If you’re planning pregnancy and are overweight, talk to your doctor about weight management. If you’re already pregnant and overweight, your baby may need extra vitamin K monitoring after birth. This doesn’t mean your baby will definitely have problems, but doctors should be aware and watch carefully.

The Research Details

Researchers looked back at hospital records from 2018 to 2023 to find babies born with vitamin K deficiency. They compared 64 babies with low vitamin K to 128 babies with normal vitamin K levels. The two groups were matched so they had similar ages and sexes, making the comparison fair. They then looked at the mothers’ health information from before pregnancy, especially their weight and body mass index (BMI). Using statistical analysis, they tested whether the mother’s weight before pregnancy was connected to the baby’s vitamin K levels.

This type of study is called a “case-control” study because researchers start with babies who have the condition (low vitamin K) and compare them to babies without it. Then they look backward to see what was different about their mothers. This approach is useful for finding possible causes of health problems.

Understanding what causes vitamin K deficiency in newborns is important because it’s a preventable problem. If doctors know which babies are at higher risk, they can monitor them more closely and give vitamin K treatment earlier if needed. This could prevent serious bleeding problems that can harm or even kill newborns.

This study has some strengths: it looked at real hospital data over several years, and the researchers carefully matched the comparison groups so they were similar except for vitamin K levels. However, the study only looked at one hospital, so the results might not apply everywhere. The researchers also couldn’t prove that obesity directly causes low vitamin K—they only showed they’re connected. More research is needed to understand exactly how obesity affects vitamin K in babies.

What the Results Show

Among the 192 babies studied, mothers of babies with vitamin K deficiency were significantly more likely to have been overweight before pregnancy. The researchers found that mothers with a BMI of 25 or higher (considered overweight or obese) had babies with low vitamin K about 4 times more often than mothers with normal weight.

When the researchers used advanced statistical methods to account for other factors that might matter, prepregnancy obesity remained strongly connected to vitamin K deficiency. This suggests that the mother’s weight before pregnancy is an independent risk factor—meaning it matters on its own, not just because of other related problems.

Additionally, the researchers found that the higher a mother’s weight before pregnancy, the lower her baby’s vitamin K levels tended to be. This shows a clear relationship: as mother’s BMI increased, baby’s vitamin K levels decreased.

The study measured vitamin K deficiency using a specific blood test called PIVKA-II. The researchers found a positive correlation between maternal BMI and PIVKA-II levels, meaning higher maternal weight was associated with higher PIVKA-II readings (which indicate lower vitamin K). This mathematical relationship strengthens the evidence that maternal weight and neonatal vitamin K are connected.

While vitamin K deficiency in newborns has been studied before, the specific connection to maternal prepregnancy obesity is relatively new. Previous research identified other maternal risk factors, but this study adds important information about obesity as a specific, independent risk factor. This finding suggests that maternal weight management before pregnancy may be another way to protect newborn health.

This study only included babies born at one hospital, so the results might not apply to all populations or regions. The researchers couldn’t determine exactly why obesity increases vitamin K deficiency risk—they only showed the connection exists. The study was also retrospective, meaning researchers looked back at old records rather than following mothers and babies forward in time. Additionally, the study didn’t examine whether vitamin K supplementation during pregnancy might help prevent this problem in overweight mothers.

The Bottom Line

Women planning pregnancy who are overweight should discuss weight management with their doctor before conception (moderate confidence—based on one study). Healthcare providers should monitor vitamin K levels more carefully in newborns whose mothers were overweight before pregnancy (moderate confidence). All newborns should receive standard vitamin K treatment at birth as currently recommended (high confidence—established practice). Pregnant women who are overweight should ensure they receive appropriate prenatal care and discuss any concerns with their healthcare provider (high confidence).

Women planning to become pregnant, especially those who are overweight or obese, should care about this research. Pregnant women who are overweight should discuss this with their healthcare provider. Healthcare providers caring for newborns should be aware of this risk factor. Parents of newborns whose mothers were overweight before pregnancy should ensure their baby receives appropriate vitamin K screening and treatment. This research is less relevant for women with normal weight before pregnancy, though all newborns still need standard vitamin K care.

Vitamin K deficiency can be detected at birth through blood tests. If a baby is identified as having low vitamin K, treatment can begin immediately. The effects of vitamin K treatment should be visible within days through follow-up blood tests. For prevention, weight management before pregnancy would need to happen months before conception to have an effect on the baby.

Want to Apply This Research?

  • Track prepregnancy BMI and weight trends for women planning pregnancy. For pregnant users, monitor vitamin K intake through diet (leafy greens, broccoli, Brussels sprouts) and note any healthcare provider recommendations for supplementation.
  • Women planning pregnancy can use the app to set weight management goals and track progress toward a healthier BMI before conception. Pregnant users can log vitamin K-rich foods daily and set reminders for prenatal appointments where vitamin K status might be discussed.
  • For women planning pregnancy: track weight and BMI monthly leading up to conception. For pregnant users: monitor dietary vitamin K intake weekly and track prenatal care appointments. For new parents: note baby’s vitamin K screening results and any follow-up testing recommended by pediatrician.

This research suggests an association between maternal prepregnancy obesity and vitamin K deficiency in newborns, but does not prove that obesity directly causes this condition. This information is for educational purposes and should not replace professional medical advice. All pregnant women and women planning pregnancy should discuss their weight, nutrition, and health with their healthcare provider. All newborns should receive standard vitamin K treatment as recommended by their pediatrician. If you have concerns about your pregnancy or your baby’s vitamin K levels, consult with your doctor or midwife immediately. This single study, while informative, represents one piece of evidence and should be considered alongside other research and clinical guidelines.