Understanding Vaccine Safety in Pregnancy

I know you’re here because you want to make the best choices for your baby. As both an ObGyn and a mother of three, I understand the anxiety that comes with vaccine decisions during pregnancy. Let me walk you through what you need to know, based on both the science and my experience.

The Science Behind Maternal Protection

When you receive a vaccine during pregnancy:

1. Your immune system creates antibodies
2. These antibodies cross the placenta
3. Your baby receives protection before birth
4. Protection continues through early infancy
5. Bridges protection gap until baby’s own vaccines

Vaccine Development and Safety Testing

Vaccines undergo rigorous testing before approval, following strict FDA standards:

1. Initial Laboratory Research
2. Animal Studies
3. Small Human Clinical Trials
4. Large-Scale Clinical Trials
5. Multiple Safety Reviews
6. Ongoing Monitoring After Release

For pregnancy specifically:

• Safety data comes from both planned studies and pregnancy registries
• Continuous monitoring through multiple reporting systems
• Regular review by independent expert committees
• Special focus on pregnancy outcomes and infant development

Understanding Vaccine Types

Inactivated Vaccines (Safe during pregnancy):

• Contain killed virus/bacteria
• Cannot cause infection
• Include flu shot and Tdap

Live Vaccines (Not given during pregnancy):

• Contain weakened live virus
• Include MMR and chickenpox vaccines
• Should be given before pregnancy when needed

Key Recommended Vaccines During Pregnancy:

1. Tdap (Tetanus, Diphtheria, Pertussis)

• • Timing: 27-36 weeks of each pregnancy
  • Purpose: Protects newborn from whooping cough
  • Safety Profile: Decades of data showing safety
  • Effectiveness: Up to 90% reduction in infant pertussis risk
  • I’ve received this with each of my pregnancies

2. Influenza (Flu Shot)

• • Timing: Any trimester during flu season
  • Let me tell you why it matters:
    • 25-89% reduction in flu risk
    • 60% reduction in newborn flu risk
    • 40% lower hospitalization risk
    • Reduced rates of pregnancy complications
  • I’ve received this with each of my pregnancies

3. COVID-19 Vaccine

• • Timing: Any trimester, recommended as soon as eligible
  • Purpose: Protects both mom and baby from severe COVID illness
  • Safety Profile: Extensive data from millions of pregnant people
  • Effectiveness:
    •    90% reduction in ICU admission risk
    •    70% reduction in severe illness
    •    Antibodies found in cord blood, protecting newborns
    •    Lower risk of pregnancy complications
  • Let me tell you why it matters:
    •    Pregnant people are at higher risk for severe COVID
    •    Reduces risk of preterm birth related to COVID infection
    •    Provides protection for baby in first months of life
    •    Safe for breastfeeding and doesn’t affect fertility

4. RSV Vaccine (Pfizer’s Abrysvo)

• • Timing: 32-36 weeks of pregnancy, ideally during RSV season (Fall/Winter)
  • Purpose: Protects newborns from severe RSV illness in first 6 months
  • Safety Profile: New but promising data from clinical trials, trend toward earlier birth in vaccinated group (this informed the recommended dosing interval of 32-36 wks). If you are higher risk for preterm birth, discuss receiving closer to 36 weeks or explore options for Abrysvo (Nirsevimab) , a monoclonal antibody that is given to baby after birth to protect against RSV.
  • Effectiveness:
    •    82% effective at preventing severe RSV in babies under 3 months
    •    57% reduction in baby’s risk of RSV hospitalization
    •    Protection lasts through baby’s most vulnerable period
  • Why it matters:
    •    RSV is the leading cause of hospitalization in infants
    •    Provides protection before baby can get their own vaccine
    •    Especially important for winter babies

Addressing Your Concerns 

About Aluminum: Let’s put this in perspective. 

In the first 6 months:

• Breast milk naturally contains 7 mg
• Formula contains 38 mg
• Vaccines contain only 4.4 mg

While aluminum from vaccines enters the bloodstream directly:

• The amount is minimal compared to daily exposure
• Kidneys remove about half within 24 hours
• The body processes it efficiently regardless of source
• Decades of research confirm safety

The truth is, your body (and your baby’s) handles this minimal amount efficiently and safely. 

What About Autism?

I believe in addressing this concern head-on. As both a doctor and a mom, I want you to know that extensive research has repeatedly shown no link between vaccines and autism. The original study suggesting this connection was thoroughly discredited and retracted. We have an abundance of data clearly showing that vaccines do not cause autism:

• Multiple large-scale studies involving millions of children
• No difference in autism rates between vaccinated and unvaccinated children
• Genetic studies showing autism development begins before birth
• Comprehensive reviews by global health organizations confirming no link

Mercury (Thimerosal) Facts

• Most modern vaccines don’t contain thimerosal
• When present, it’s ethylmercury which:
  •   Is quickly cleared from the body
  •   Different from toxic methylmercury in fish
  •   Has been extensively studied for safety
• You can request thimerosal-free versions if concerned

The Mental Load of Vaccine Decisions

Making these decisions can feel overwhelming. You’re may be:

• Researching extensively
• Finding conflicting information
• Feeling anxious about making the “right” choice
• Wanting to protect your baby while ensuring safety

It’s important to know that your concerns are valid, and you’re not alone in feeling this way.

My Professional + Personal Take

As an ObGyn who has supported thousands of pregnancies and experienced three of my own, I can tell you that vaccines are one of our most powerful tools for protecting both mom and baby. The evidence supporting their safety is robust, and I’ve seen how they prevent serious complications. I know a lot of pediatricians, some of them infectious disease specialists and even a few immunologists who work in vaccine research and guess what… they all vaccinate their kids and receive the recommended vaccines in pregnancy. I promise you, we would not be giving this to our own children and receiving them ourselves if we didn’t whole-heartedly believe in the safety and efficacy of vaccines.

What You Can Do Today

1. Schedule a conversation with your OB provider about your specific concerns
2. Write down your questions (seriously, all of them!)
3. Remember that anxiety about these decisions is normal
4. Know that you have support in making these choices