What perinatal prophylaxis is recommended for pregnant individuals?

Perinatal Prophylaxis Recommendations

Group B Streptococcus (GBS) Prevention

All pregnant women should be screened at 36 0/7 to 37 6/7 weeks' gestation for vaginal and rectal GBS colonization, with intrapartum antibiotic prophylaxis administered to all GBS carriers during labor. 1

Universal Screening Protocol

• Screen all pregnant women between 36-37 weeks' gestation using both vaginal and rectal swabs (through the anal sphincter), placed in nonnutritive transport medium 2, 1
• Specimens should be clearly labeled for GBS culture and processed using selective enrichment broth to maximize recovery 2
• Collection can be performed by the patient with proper instruction or by a healthcare provider, but should not involve speculum examination 2

Indications for Intrapartum Antibiotic Prophylaxis

Automatic prophylaxis (no screening needed):

• Women with GBS bacteriuria at any concentration during current pregnancy 2, 1
• Women with previous infant affected by invasive GBS disease 2, 1

Prophylaxis based on screening results:

• All women with positive GBS screening at 36-37 weeks 2, 1
• Colonization in a previous pregnancy does NOT indicate prophylaxis in subsequent deliveries 2

Prophylaxis when GBS status unknown at labor onset:

• Gestational age <37 weeks 2, 1
• Membrane rupture ≥18 hours 2
• Intrapartum temperature ≥100.4°F (≥38.0°C) 2
• Women with negative GBS screening within 5 weeks of delivery do NOT require prophylaxis even with these risk factors 2

Antibiotic Regimens for GBS Prophylaxis

First-line therapy (non-allergic patients):

• Penicillin G: 5 million units IV initial dose, then 2.5-3 million units IV every 4 hours until delivery 1
• Alternative: Ampicillin 2g IV initial dose, then 1g IV every 4 hours until delivery 1

Penicillin-allergic patients:

• Clindamycin 900mg IV every 8 hours (requires susceptibility testing due to increasing resistance) 1
• Vancomycin 1g IV every 12 hours (reserved for significant penicillin allergy) 1
• Cefazolin 2g IV initial dose, then 1g IV every 8 hours (for non-severe penicillin allergy) 1

Critical timing consideration:

• Prophylaxis is most effective when administered ≥4 hours before delivery 2, 3
• Begin IV antibiotics immediately upon admission in labor or membrane rupture for GBS-positive women 2, 1

Special Situations

Threatened preterm labor (<37 weeks):

• Obtain vaginal-rectal GBS culture immediately 2, 1
• Start GBS prophylaxis while awaiting results 1
• If not in true labor, discontinue prophylaxis 1

Preterm premature rupture of membranes (pPROM):

• Obtain GBS culture and initiate antibiotics 1
• Ampicillin 2g IV once, then 1g IV every 6 hours for ≥48 hours provides adequate GBS prophylaxis when given for latency 1

GBS urinary tract infection during pregnancy:

• Treat all GBS bacteriuria regardless of colony count according to standard UTI protocols 2, 1
• These women require intrapartum prophylaxis and do NOT need repeat screening at 36-37 weeks 2, 1

Critical Pitfalls to Avoid

• Never attempt to eradicate GBS colonization with antibiotics before labor - this is ineffective and may cause adverse consequences including antibiotic resistance 1
• Do not withhold intrapartum prophylaxis for women with GBS bacteriuria in current pregnancy, even if subsequent cultures are negative 1
• Do not provide prophylaxis based solely on previous pregnancy colonization without current screening 2
• Avoid amniocentesis and invasive fetal monitoring when membranes are intact, as these increase transmission risk 2

HIV Prevention in Pregnancy

All HIV-infected pregnant women should receive combination antiretroviral therapy including zidovudine, with continuous IV zidovudine during labor and 6 weeks of infant prophylaxis to prevent perinatal transmission. 4

Antiretroviral Therapy Regimen

Antepartum management:

• Initiate combination antiretroviral therapy (cART) after first trimester for all HIV-infected pregnant women 4
• Standard combination regimens should include zidovudine as a component 4
• The landmark PACTG 076 trial demonstrated zidovudine monotherapy reduced transmission from 25.5% to 8.3% 4

Intrapartum management:

• Begin continuous IV zidovudine infusion 3 hours before scheduled cesarean delivery or at labor onset 4
• Continue other antiretroviral medications without interruption during delivery 2

Infant prophylaxis:

• Administer oral zidovudine to infants for 6 weeks when mothers received adequate antenatal antiretroviral therapy 4
• For infants whose mothers received no antiretroviral therapy: either single-dose nevirapine (2 mg/kg) at birth PLUS zidovudine for 6 weeks, OR zidovudine alone for 6 weeks 4

Mode of Delivery Considerations

Scheduled cesarean delivery at 38 weeks' gestation is recommended when:

• HIV RNA viral load >1,000 copies/mL at 34-36 weeks' gestation 2, 4
• Cesarean should be performed before labor onset and membrane rupture 4
• Begin IV zidovudine 3 hours before surgery 2, 4

Vaginal delivery considerations:

• Avoid artificial rupture of membranes when possible 2
• Avoid invasive fetal monitoring and amniocentesis 2
• Duration of membrane rupture ≥4 hours increases transmission risk 2

Additional Prevention Measures

• HIV testing should be offered to all pregnant women with opt-out approach to maximize identification 2
• Breastfeeding is not recommended for HIV-infected women in resource-rich settings like the United States 4
• Early prenatal care is essential - 15% of HIV-infected pregnant women receive no prenatal care compared to 2% of general population 2

Hepatitis B Prevention in Pregnancy

Infants born to HBsAg-positive mothers should receive hepatitis B immune globulin (HBIG) 0.5 mL IM within 12 hours of birth plus hepatitis B vaccine series starting within 7 days. 5

Perinatal Hepatitis B Prophylaxis

For infants of HBsAg-positive mothers:

• Administer HBIG 0.5 mL IM within 12 hours of birth (efficacy decreases markedly if delayed beyond 48 hours) 5
• Begin hepatitis B vaccine series: 0.5 mL (10 μg) IM within 7 days of birth 5
• Subsequent vaccine doses at 1 month and 6 months after first dose 5
• HBIG and vaccine may be given concurrently but at separate sites 5

If vaccine is delayed or refused:

• Repeat HBIG 0.5 mL dose at 3 months if first vaccine dose delayed up to 3 months 5
• If vaccine refused entirely, repeat HBIG at 3 and 6 months 5

Maternal Screening and Management

• All pregnant women should be screened for HBsAg to identify at-risk infants before delivery 5
• Infants at highest risk when mother is both HBsAg-positive and HBeAg-positive 5
• Combined HBIG plus vaccine regimen is 85-95% effective in preventing chronic HBV carrier state 5

Healthcare Worker Exposure

For needlestick or mucous membrane exposure to HBsAg-positive blood:

• Unvaccinated persons: HBIG 0.06 mL/kg IM immediately (within 24 hours if possible) plus initiate hepatitis B vaccine series 5
• Vaccinated persons with inadequate antibody response: HBIG immediately plus vaccine booster, or 2 doses of HBIG (immediately and at 1 month) 5