Management of syphilis during pregnancy

If congenital syphilis is suspected a specialist should be consulted.

All women should have a syphilis screen in the first trimester.

Women at high risk, for example Aboriginal women, should have a further test in the third trimester.

Women with a positive test should be evaluated rapidly on history and examination, with testing of contacts and, if unresolved a further RPR (two weeks after the first test).

Syphilis in pregnancy should be treated with the standard regimen used for the same clinical stage of syphilis in non-pregnant women.

The only exception is early syphilis diagnosed in the third trimester of pregnancy, which should be treated with: 

Benzathine penicillin G 1.8 gm (2.4 million units) im weekly for two weeks.

Coordination of pre-natal and post-natal care is vital. When syphilis is diagnosed in the second half of pregnancy an ultrasound evaluation for congenital syphilis should be done, but should not delay treatment.

If active syphilis cannot be reasonably excluded by this process the patient should be treated for early syphilis, as a safeguard against foetal infection.

Pregnant women with a history of penicillin allergy should be desensitised and treated with penicillin. No proven alternatives for maternal or foetal infection exist.

Women treated for syphilis in pregnancy should have follow up RPR at 28 to 32 weeks gestation and at delivery, and beyond for their clinical stage of syphilis.

Women treated during the second half of pregnancy are at risk of premature labour and foetal distress, due to a Jarisch-Herxheimer reaction. Patients over 20 weeks of pregnancy requiring treatment for syphilis should be discussed with the attending Obstetrician prior to treatment, but treatment should not be delayed.

HIV testing should be offered to all patients with syphilis, including pregnant women.

If the mother completes treatment with penicillin more than four weeks before delivery, risk to the infant is minimal, and follow up of the infant involves clinical examination at birth, serology at birth and thereafter three monthly until RPR is negative.

If maternal treatment was:

  • inadequate
  • unknown
  • with a non-penicillin regimen
  • completed less than four weeks prior to delivery
  • or if adequate follow up of the infant cannot be assured.

The infant should be treated at birth and have repeat serology three monthly until the RPR becomes negative. The CSF should be examined before treatment if there is a substantial risk of congenital syphilis.

Aqueous crystalline penicillin G 50,000 units/kg i.v. 12 hourly for the first seven days of life and every eight hours thereafter for a total of ten days


Aqueous procaine penicillin G 50,000 units/kg im in a single daily dose for ten days.

For asymptomatic infants with normal CSF and for whom follow up cannot be guaranteed:

Benzathine penicillin G 50,000 units/kg im as one dose.

Further information

For further information on the management of syphilis during pregnancy contact Adelaide Sexual Health Centre.


These guidelines are based on review of current literature, current recommendations of the United States Centers for Disease Control and Prevention, World Health Organization, the British Association for Sexual Health and HIV and local expert opinion.

They are written primarily for use by Adelaide Sexual Health Centre staff and some flexibility is required in applying them to certain private practice situations.

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