Fish Oil and Probiotics During Pregnancy: Effects on Kids' Allergies

observational-study PMID: 37622257

Fish Oil and Probiotics During Pregnancy: Effects on Kids' Allergies

Quick Summary: This study looked at whether taking fish oil or probiotics during early pregnancy could prevent allergies in babies up to age two. Fish oil didn't help with allergies, but probiotics lowered the chance of repeated wheezing in toddlers at 24 months. Overall, these supplements didn't reduce food allergies, eczema, or related issues.

What The Research Found

Researchers tested if fish oil, probiotics, or both could cut down on allergic problems in young children. The main takeaway? No big wins for preventing most allergies, but one clear benefit stood out.

Probiotics made a difference for wheezing: Moms who took specific probiotics had kids with 61% lower odds of recurrent wheezing (like early asthma signs) by age two. This wasn't seen at 12 months.
Fish oil showed no allergy benefits: Taking fish oil alone or with probiotics didn't lower risks for food allergies, eczema, or sensitivity to allergens (called atopy) at 12 or 24 months.
Combo didn't outperform singles: Mixing fish oil and probiotics worked the same as taking just one—no extra protection against allergies.

These results come from careful checks by doctors on the kids' health.

Study Details

Who was studied: 439 pregnant women in early pregnancy, with healthy outcomes tracked in their babies. It was a double-blind trial, meaning neither moms nor researchers knew who got real supplements versus fakes to keep results unbiased.
How long: Supplements started in early pregnancy and continued through birth; kids were followed for two years (checked at 12 and 24 months).
What they took: Women were split into four groups daily:
Fish oil: 1.9 grams of DHA (a key omega-3) and 0.22 grams of EPA (another omega-3 from fish).
Probiotics: 1 billion colony-forming units (CFU) of Lacticaseibacillus rhamnosus HN001 and Bifidobacterium animalis ssp. lactis 420—good bacteria for gut health.
Both together.
Placebo (fake pills with no active ingredients).

What This Means For You

If you're pregnant and worried about your child's allergies or breathing issues, this study offers some guidance but not a magic fix. Probiotics might help prevent wheezing episodes in toddlers, which could mean fewer doctor visits for respiratory problems. Fish oil, often praised for heart and brain health, didn't prevent allergies here—stick to it for other proven benefits if your doctor recommends.

For expecting moms: Talk to your healthcare provider about strain-specific probiotics like these if family history includes asthma or wheezing. Start early in pregnancy for potential breathing benefits.
For parents of young kids: If your child wheezes often, this hints probiotics during pregnancy could have helped, but it's not a cure-all. Focus on overall health like breastfeeding and avoiding smoke.
Bottom line: Don't rely on these for broad allergy prevention—lifestyle and medical advice matter more. More research is needed for long-term effects, like on asthma later in childhood.

Study Limitations

Every study has limits, and this one is no exception—here's what to keep in mind so you don't overhype the results.

Small group size: With 439 moms, it might miss subtle effects on rare allergies, so bigger studies could reveal more.
Short timeline: Only up to two years— we don't know if benefits (like less wheezing) last into school age or if allergies pop up later.
Specific to this group: Results are from these exact supplements and a general pregnancy population; they might not apply to high-risk families, different probiotic strains, or other doses.
Mixed past evidence: Some earlier studies saw allergy benefits from these, but this one didn't—differences in how things were measured or who joined could explain that.
Not a full picture: It focused on doctor-diagnosed issues, so milder symptoms might have been overlooked.

This research is a step forward, but always check with a doctor before starting supplements during pregnancy.

Key Findings

The study found that maternal supplementation with probiotics (Lacticaseibacillus rhamnosus HN001 and Bifidobacterium animalis ssp. lactis 420) during pregnancy was associated with lower odds of recurrent wheezing in children at 24 months (OR 0.39, 95% CI 0.18–0.84, p=0.017). However, neither fish oil (1.9g DHA + 0.22g EPA) nor probiotics, alone or combined, reduced the risk of food allergy, atopic eczema, or atopy at 12 or 24 months.

Study Design

This was a double-blind randomized controlled trial (RCT) involving 439 pregnant women in early pregnancy. Participants were assigned to four groups: fish oil + placebo, probiotics + placebo, fish oil + probiotics, or placebo + placebo. Outcomes were assessed in infants at 12 and 24 months. The study duration spanned pregnancy and up to two years postpartum.

Dosage & Administration

Fish oil: 1.9g docosahexaenoic acid (DHA) and 0.22g eicosapentaenoic acid (EPA) daily.
Probiotics: 10⁹ CFU/day of L. rhamnosus HN001 and B. animalis ssp. lactis 420.
Supplements were administered daily from early pregnancy onwards, with follow-up until the infants reached 24 months.

Results & Efficacy

Recurrent wheezing: Probiotics alone reduced odds at 24 months (OR 0.39, 95% CI 0.18–0.84, p=0.017), but not at 12 months.
Other allergic diseases: No significant differences in physician-diagnosed food allergy, atopic eczema, or atopy at 12/24 months across groups (all p>0.05).
Combined interventions: Fish oil + probiotics did not enhance efficacy compared to single interventions.

Limitations

Observational classification error: Despite being labeled observational, the study was a double-blind RCT, limiting clarity on design accuracy.
Sample size: 439 participants may have been underpowered to detect small differences in rare outcomes (e.g., specific allergies).
Population specificity: Results may not generalize to non-high-risk cohorts or other strains/doses.
Short follow-up: Long-term effects on asthma or allergies beyond two years remain unknown.
Outcome variability: No effect on eczema or atopy contradicts some prior research, suggesting possible heterogeneity in mechanisms.

Clinical Relevance

Maternal probiotic supplementation (with L. rhamnosus HN001 and B. animalis 420) may reduce recurrent wheezing in offspring by age two, but does not prevent food allergies or eczema. Fish oil (DHA/EPA) showed no benefit for allergic outcomes. These findings suggest that probiotics during pregnancy could target respiratory health in early childhood, though larger trials and longer follow-up are needed to confirm effects on asthma. For supplement users, strain-specific probiotics might be considered for respiratory support, but broad allergy prevention claims remain unsupported.

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