Researchers in Sweden studied 123 pregnant women to understand how vitamin D deficiency affects childbirth. They found that women with severely low vitamin D levels (a condition called osteomalacia) were much more likely to need help during delivery, including vacuum extraction or emergency cesarean sections. This is especially important because women from certain backgrounds living in northern countries with less sunlight are at higher risk. The study suggests that checking vitamin D levels during pregnancy and providing supplements could help prevent delivery complications.

The Quick Take

  • What they studied: Whether severe vitamin D deficiency during pregnancy makes childbirth more complicated and increases the need for medical assistance during delivery
  • Who participated: 123 pregnant women in Sweden: 71 Swedish women and 52 Somali women. The researchers focused on these two groups because Somali women living in Sweden have much higher rates of vitamin D deficiency due to less sun exposure and darker skin pigmentation
  • Key finding: Women with severe vitamin D deficiency were nearly 5 times more likely to need forceps or other tools to help with delivery, and 16 times more likely to need vacuum-assisted delivery compared to women with normal vitamin D levels
  • What it means for you: If you’re pregnant or planning to become pregnant, especially if you live in a northern climate or have darker skin, getting your vitamin D levels checked and taking supplements if needed may help reduce the chance of needing assisted delivery. However, this is one study and more research is needed to confirm these findings

The Research Details

This was a prospective cohort study, which means researchers followed women forward in time from the beginning of pregnancy through delivery. They collected blood samples and health information from 123 pregnant women in Sweden at the start of the study, then tracked what happened during their deliveries about two years later. The researchers specifically compared Swedish women (who typically have higher vitamin D levels) with Somali women (who have higher rates of vitamin D deficiency). They used a special method to diagnose vitamin D deficiency that didn’t require radiation or invasive procedures—just blood tests and physical examination.

The researchers looked at medical records to see which women needed help during delivery, such as forceps, vacuum extraction, or emergency cesarean sections. They then used statistical analysis to determine whether vitamin D deficiency was connected to these delivery complications, while accounting for other factors that might affect delivery outcomes.

This research approach is important because it follows real pregnant women through their actual pregnancies and deliveries, rather than just looking at data after the fact. By comparing two groups with different vitamin D levels, the researchers could see if there was a real connection between vitamin D deficiency and delivery problems. The study is particularly valuable because it focuses on a group (Somali women in northern climates) that hasn’t been studied much before but faces significant vitamin D deficiency risks.

Strengths of this study include that it followed women prospectively (forward in time), used objective blood tests to measure vitamin D, and examined a high-risk population that’s often overlooked. The study was relatively small (only 20 women had severe vitamin D deficiency), which means the results should be interpreted cautiously. The researchers adjusted their analysis for some confounding factors, though they noted using a ‘minimal set’ of adjustments. The study was conducted in Sweden, so results may not apply equally to all populations or climates

What the Results Show

Among the 123 women studied, 20 were diagnosed with severe vitamin D deficiency (biochemical osteomalacia)—19 were Somali women and 1 was Swedish. This shows that Somali women in Sweden face much higher risk of severe vitamin D deficiency.

Women with severe vitamin D deficiency had significantly higher rates of needing assisted delivery. Specifically, they were nearly 5 times more likely to need forceps or other instruments to help with delivery (adjusted odds ratio of 4.92). Even more striking, they were 16 times more likely to need vacuum-assisted delivery, where a suction cup helps guide the baby out.

The study also found that women with vitamin D deficiency had higher rates of emergency cesarean sections (surgical delivery). These findings suggest that vitamin D deficiency may weaken the muscles needed for normal childbirth or affect the birth canal in ways that make delivery more difficult.

The research confirmed that vitamin D deficiency was particularly common among Somali women living in Sweden, with 95% of women diagnosed with severe deficiency being from this group. This highlights how migration to northern climates combined with genetic factors (darker skin requires more sun exposure to produce vitamin D) creates a significant health risk. The study also noted that vitamin D deficiency can affect both smooth muscle (involuntary muscles) and skeletal muscle (voluntary muscles), which could explain why it impacts the ability to push during labor

While vitamin D deficiency has been studied in many health contexts, its specific connection to delivery complications hasn’t been thoroughly explored, especially in migrant populations. This study adds important new evidence that vitamin D deficiency may be a previously overlooked risk factor for needing assisted delivery. The findings align with what we know about vitamin D’s role in muscle function and calcium metabolism, which are crucial for labor

The study had a relatively small number of women with severe vitamin D deficiency (only 20), which makes the results less certain, especially for the vacuum extraction finding. The study was conducted only in Sweden, so results may not apply to other countries or climates. The researchers excluded women who had miscarriages, stillbirths, or moved away, which could have affected the results. The study shows association (connection) but cannot prove that vitamin D deficiency directly causes delivery complications—other factors could be involved

The Bottom Line

Moderate confidence: Pregnant women, especially those living in northern climates or with darker skin, should have their vitamin D levels checked during pregnancy. If levels are low, vitamin D supplementation appears to be a safe and potentially beneficial intervention. Healthcare providers should screen for vitamin D deficiency during pregnancy and early breastfeeding and provide supplements when needed. High confidence: This is a reasonable precaution given vitamin D’s known importance for bone health, muscle function, and overall health during pregnancy

This research is most relevant for: pregnant women living in northern climates with limited sun exposure; women with darker skin pigmentation; women from African or Middle Eastern backgrounds; women who cover their skin for cultural or religious reasons; and healthcare providers caring for pregnant women. The findings may be less relevant for women living in sunny climates or those with lighter skin pigmentation who get adequate sun exposure

Vitamin D supplementation during pregnancy should begin as early as possible—ideally before pregnancy or in the first trimester. It takes several weeks to months to build up adequate vitamin D levels in the body. Benefits for reducing delivery complications would be expected if supplementation is started early enough in pregnancy

Want to Apply This Research?

  • Track vitamin D supplementation daily (dose and type), along with sun exposure time and skin coverage. Users can log whether they took their vitamin D supplement each day and note any symptoms of deficiency (muscle weakness, bone pain, fatigue)
  • Set a daily reminder to take vitamin D supplements at the same time each day. For pregnant users, log vitamin D intake alongside prenatal vitamin use to ensure consistent supplementation throughout pregnancy and breastfeeding
  • Create a long-term tracking system that records vitamin D supplement adherence, seasonal changes in sun exposure, and any symptoms. Users should also track follow-up blood test results to monitor vitamin D levels over time, with reminders to retest every 3-6 months during pregnancy

This research suggests an association between vitamin D deficiency and delivery complications, but cannot prove direct causation. These findings are based on a single study with a small number of women with severe deficiency. Pregnant women should consult with their healthcare provider about vitamin D screening and supplementation, as individual needs vary. This information is not a substitute for professional medical advice, diagnosis, or treatment. Always discuss any pregnancy-related concerns with your doctor or midwife before making changes to your health routine