Congenital syphilis

The incidence of congenital syphilis, which is largely preventable, is high in the Russian Federation. (1) Because many infected pregnant women are treated inadequately or too late in their pregnancy, 64% deliver babies with presumptive or confirmed congenital syphilis. According to a review of records from five maternity hospitals in the Russian Federation, the odds of delivering a baby with congenital syphilis are elevated among infected women who go without prenatal care (odds ratio, 2.8) and among those who are first tested for syphilis at 28 weeks' gestation or later (4.0). Overall, 26% of the infants of women with untreated or inadequately treated syphilis die shortly after birth or in utero.

Women who were at least 20 weeks pregnant between January 1995 and October 1999 and delivered in maternity hospitals in two metropolitan areas (Moscow and St. Petersburg) and three nonmetropolitan areas (Novgorod, Moscow Oblast and Ryazan) were eligible for the study. (Deliveries included fetal deaths and induced abortions at 20 or more weeks' gestation.) A consecutive sampling of the hospitals' medical records yielded a sample of 850 women who had active syphilis, according to additional records from prenatal, women's health or sexually transmitted disease (STD) clinics. Active infections included new diagnoses during the index pregnancy and previous infections that had been untreated or inadequately treated (i.e., the woman was not given long- or short-acting penicillin within 30 days of delivery).

The researchers used results of clinical tests for confirmed congenital infection (physical examinations and serologic evaluations) and the World Health Organization definition of presumptive congenital infection, which includes any infant born to a woman with untreated or inadequately treated syphilis, to assess the rate of congenital infection according to maternal characteristics and pregnancy outcomes. They performed bivariate and multivariate logistic analyses to determine risk factors associated with congenital syphilis.

Most of the women (77-79%) were married, were aged 20 or older, and resided in the cities where they sought care. Thirty-six percent each were homemakers and were unemployed; 12% described themselves as professionals, 10% as manual laborers and 5% as students. Fifty-seven percent of the sample had had inadequate prenatal care: Forty percent had had none at all, and 17% had initiated care at 21 weeks' gestation or later. A substantial proportion of the women--45%--had first been tested for syphilis at 28 weeks' gestation or later; the same proportion had not received any antibiotic treatment for their infection. Further, 59% had not received the preferred antibiotic, penicillin G; the proportion not receiving it was 77% among women who had not received any prenatal care. Most of the infected women had an early latent infection (59%), whereas 34% were diagnosed with secondary syphilis and 6% with primary syphilis.

Overall, 64% of the infected pregnant women delivered an infant with presumptive or confirmed congenital syphilis. This proportion was significantly elevated among women who had not had any prenatal care (86%), who were nonresidents (83%) and who were first tested for syphilis at 28 weeks' gestation or later (83%). There were significant trends both toward increasing incidence with later prenatal care (41% among infants of women who sought care at 20 weeks or earlier vs. 63% among infants of women who obtained care at 21 weeks or later) and toward decreasing incidence with the number of prenatal visits (78% among infants of women who made three or fewer visits vs. 53% among infants of women who made at least four). Further, the incidence of congenital syphilis was significantly higher among babies of women with late latent syphilis than among those of women with primary or secondary syphilis (67% vs. 42-48%). Finally, the rate of infection differed significantly by the setting in which the mother was diagnosed (48% among infants of women diagnosed in an STD clinic, 60% among those of patients diagnosed in women's health clinics and 82% among those of women seen in other institutions).

Among all infected women for whom pregnancy outcomes were known, 65% had a live birth, 15% an induced abortion, 11% a stillbirth, 6% a late fetal death (at 20 or more weeks' gestation) and 2% a liveborn baby who later died. Among women whose infant met the case definition for presumptive congenital syphilis, 26% had an outcome of fetal or infant death--16% had a stillbirth, 7% a baby who died in utero at 20 weeks' gestation or later, and 3% a baby who was born alive and later died.

Results of the multivariate analysis, which controlled for the mother's age, residence and marital status, indicate that three factors independently increased the odds that an infected woman would deliver an infected infant. These were lack of prenatal care (adjusted odds ratio, 2.8), first being tested for syphilis late in the pregnancy (4.0) and having latent syphilis, as opposed to primary or secondary syphilis (3.7).

The investigators acknowledge that their study is limited by its retrospective design, the lack of data on substance abuse and a possible bias caused by the inclusion of women who were false positives (which would have underestimated the true incidence of congenital syphilis). They note that congenital syphilis "should be largely preventable" and that the "mainstay" of prevention--early diagnosis and appropriate treatment--needs to be strengthened among the range of Russian health care institutions that provide prenatal care. They conclude by noting that this recommended prevention strategy and infrastructure will also be essential for controlling perinatal transmission of HIV, which is expected to increase in the Russian Federation.

REFERENCE

(1.) Tikhonova L et al., Congenital syphilis in the Russian Federation: magnitude, determinants and consequences, Sexually Transmitted Infections, 2003, 79(2): 106-110.

COPYRIGHT 2003 Alan Guttmacher Institute
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