Pregnancy is a time of excitement, anticipation, and careful planning. But alongside buying onesies and picking names, there’s a critical aspect of prenatal care that often goes undiscussed: sexually transmitted diseases (STDs). STDs during pregnancy can pose serious risks to both mother and baby, including preterm birth, developmental issues, and life-threatening infections. Yet with proper education, testing, and prevention, many of these risks can be minimized or avoided entirely.
In this article, we’ll explore how STDs impact pregnancy, which infections are most dangerous to babies, and how to protect yourself and your child. Drawing on data from the CDC, WHO, and leading obstetric experts, we’ll break down complex medical concepts into actionable advice—because every parent deserves a healthy start.
Why STDs During Pregnancy Are a Silent Threat
STDs are often called “silent” infections because many show no symptoms. For example, up to 70% of women with chlamydia don’t realize they’re infected. During pregnancy, this invisibility becomes dangerous. Without testing, infections can go untreated, spreading to the uterus, amniotic fluid, or baby during delivery.
Dr. Laura Riley, Chief of Obstetrics at Massachusetts General Hospital, explains: “The placenta isn’t a perfect shield. Bacteria and viruses like syphilis or HIV can cross into the fetal bloodstream, causing irreversible harm.”
Key Statistics:
- 1 in 4 pregnant women with syphilis experience stillbirth or infant death.
- 40% of untreated chlamydia cases lead to preterm labor.
- HIV transmission to babies has dropped to <1% with proper antiretroviral therapy (ART).
STDs That Pose the Greatest Risks During Pregnancy
Not all STDs affect pregnancy equally. Here’s a breakdown of the most concerning infections and their potential impact:
1. Syphilis: The Stealthy Destroyer
Syphilis is a bacterial infection that can cross the placenta as early as the first trimester. Untreated, it causes congenital syphilis, linked to stillbirth, bone deformities, and neurological damage. Cases have surged in recent years, with the CDC reporting a 203% increase in congenital syphilis between 2016 and 2022.
Real-World Example:
A 2023 study in JAMA Pediatrics detailed a case where a mother’s undiagnosed syphilis led to her newborn suffering seizures and blindness. Routine prenatal testing could have prevented this.
Prevention Strategy:
- Mandatory syphilis testing in the first trimester and again at 28 weeks.
- Penicillin injections (the only treatment safe during pregnancy).
2. HIV: From Crisis to Hope
HIV can pass to the baby during pregnancy, labor, or breastfeeding. Without intervention, transmission rates are 15–45%. However, ART reduces this risk to under 1%.
Expert Insight:
Dr. Elaine Abrams, a pioneer in pediatric HIV research, notes: “Starting ART early in pregnancy isn’t just about the mom—it’s about giving the baby a lifetime free of HIV.”
Prevention Strategy:
- Universal HIV testing at the first prenatal visit.
- Daily antiretroviral regimens for the mother.
- Avoiding breastfeeding if alternatives are available.
3. Hepatitis B: A Preventable Threat
Hepatitis B (HBV) can cause chronic liver disease in infants exposed during birth. Thankfully, vaccines are 90% effective at preventing transmission when given within 12 hours of delivery.
Prevention Strategy:
- HBV vaccine and hepatitis B immune globulin (HBIG) for the newborn.
4. Herpes (HSV): A Delivery Room Danger
Genital herpes rarely crosses the placenta but can infect babies during vaginal delivery if sores are present. Neonatal herpes causes brain damage or death in 60% of untreated cases.
Case Study:
A 2021 report in Obstetrics & Gynecology highlighted a mother with asymptomatic HSV who transmitted the virus during labor. The baby survived after weeks of antiviral treatment but had lasting neurological issues.
Prevention Strategy:
- Antiviral medications (e.g., acyclovir) in the third trimester for women with HSV.
- Cesarean delivery if active sores are present.
5. Chlamydia and Gonorrhea: Silent Risks to Newborns
These bacterial infections are linked to preterm birth, low birth weight, and eye or lung infections in babies. Up to 50% of infants born vaginally to untreated mothers develop conjunctivitis.
Prevention Strategy:
- Routine first-trimester screening.
- Antibiotics like azithromycin (safe during pregnancy).
How STDs Reach the Baby: Pathways and Timing
Understanding how infections spread helps explain prevention tactics:
- In Utero (During Pregnancy):
- Syphilis, HIV, and Zika cross the placenta.
- Risks: Organ damage, miscarriage, stillbirth.
- During Delivery:
- Herpes, gonorrhea, and chlamydia transmit via contact with vaginal fluids.
- Risks: Pneumonia, blindness, sepsis.
- Postpartum (Breastfeeding):
- HIV and HTLV-1 (a rare virus) pass through breast milk.
Prevention Strategies: A Step-by-Step Guide
1. Prenatal Testing: The First Line of Defense
The CDC recommends universal screening for syphilis, HIV, hepatitis B, and chlamydia at the first prenatal visit. High-risk women (e.g., multiple partners or past STD diagnoses) should also be tested for gonorrhea and herpes.
Why It Works:
- Early detection allows treatment before the baby is exposed.
- Example: Treating syphilis with penicillin before 18 weeks prevents 98% of congenital cases.
2. Vaccination: Guarding Against Preventable STDs
- HPV Vaccine: Prevents genital warts and cervical cancer. Safe before pregnancy but not during.
- Hepatitis B Vaccine: Safe during pregnancy; protects mom and baby.
3. Safe Sex During Pregnancy
Condoms remain critical, even during pregnancy, to prevent new infections. Partners should also get tested and treated if needed.
Myth Buster:
“You can’t get pregnant if you’re already pregnant” is false. Women can conceive again (superfetation) and acquire new STDs.
4. Partner Treatment: Breaking the Chain of Infection
If a partner has an STD, reinfection can occur. Expedited partner therapy (EPT)—where doctors prescribe treatment for the partner without an exam—is legal in most states.
5. Avoiding High-Risk Behaviors
- Sharing needles (for drugs or tattoos).
- Unprotected sex with partners of unknown STD status.
Treatment During Pregnancy: What’s Safe and What’s Not
Many antibiotics and antivirals are pregnancy-safe, but dosage and timing matter:
- Safe: Penicillin (syphilis), azithromycin (chlamydia), acyclovir (herpes).
- Unsafe: Doxycycline (gonorrhea) and fluconazole (yeast infections) in the first trimester.
Expert Tip:
“Always tell your OB-GYN about any medications or supplements you’re taking,” advises Dr. Jennifer Ashton, OB-GYN and ABC News correspondent.
The Role of Stigma: Why Open Conversations Matter
Fear of judgment prevents many women from disclosing sexual histories or requesting STD tests. A 2022 BJOG study found that 30% of pregnant women avoided discussing STDs with their providers due to shame.
How to Advocate for Yourself:
- “I’d like to review my STD test results together.”
- “Could we discuss ways to lower my infection risk during pregnancy?”
The Bottom Line
While STDs in pregnancy can feel overwhelming, modern medicine offers powerful tools to protect babies. Routine testing, timely treatment, and honest communication with providers are the pillars of prevention. By prioritizing these steps, parents-to-be can focus on what truly matters: welcoming a healthy new life.