General Obstetrics and Gynecology: Obstetrics
The Alabama Preterm Birth Study: Intrauterine infection and placental histologic findings in preterm births of males and females less than 32 weeks

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Objective

The objective of the study was to determine whether there are differences in the placental histology and various markers of infection/inflammation between preterm male and female fetuses.

Study design

The placentas and umbilical cords of 446 infants born at 23 to 32 weeks were examined histologically, cultured for aerobic and anaerobic bacteria and mycoplasmas, and the interleukin-6 levels in cord blood determined.

Results

Male infants were significantly more likely to have positive placental cultures than female infants (63.4% versus 51.8%, P = .01, odds ratio 1.5, 1.0 to 2.4). Cord blood Mycoplasma hominis and Ureaplasma urealyticum infections were marginally more common in male than female fetuses (27.6% versus 19.2%, P = .06, odds ratio 1.7, 0.9 to 2.9), but cord blood interleukin-6 levels were not different between male and female fetuses. The only significant histologic difference between male and female placentas was in decidual lymphoplasmacytic cell infiltration (6.3% versus 0.9%, P = .003, odds ratio 8.3, 1.8 to 39.0). Males had a higher percentage of decidual lymphohistiocytic cell infiltration, but the differences were not significant (11.3% versus 7.4%, P = .160, odds ratio 1.6, 0.8 to 3.2).

Conclusion

Male infants were significantly more likely to have positive placental membrane cultures than female infants. Decidual lymphoplasmacytic cell infiltrations were more common in male versus female placentas, confirming a previous observation and suggesting that a maternal immune reaction to fetal tissue may be more common in male fetuses.

Section snippets

Material and methods

From December 5, 1996, to June 13, 2001, 457 consecutive deliveries of infants born between 23 and 32 weeks were evaluated.14 A chart review was performed by trained research nurses to gather demographic characteristics such as maternal race, age, parity, smoking status, diabetes, and pre-eclampsia and determine whether the delivery was spontaneous or indicated. Spontaneous preterm birth was defined as delivery after either spontaneous preterm labor or spontaneous preterm premature rupture of

Results

Table I shows the characteristics of the mothers of the male and female infants enrolled in this study. Male infants were more likely to come from spontaneous rather than indicated deliveries, (P = .025) and weighed about 100 g more (P = .008). There were no differences in corticosteroid or antibiotic use between male and female infants.

We next evaluated the relationship between infant sex and various markers of infection/inflammation. Male infants were significantly more likely to have a

Comment

In this study of 23- to 32-week deliveries, male infants were significantly more likely to be born following a spontaneous rather than indicated delivery and were also significantly more likely to have placental membrane bacterial infection. Because most early spontaneous preterm births are associated with, and probably caused by, placental membrane infection associated with acute placental inflammation,11, 12, 27 these data suggest that a portion of the increase in male versus female early

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  • Cited by (0)

    Reprints not available from the authors. Address correspondence to Robert L. Goldenberg, MD, Department of Obstetrics/Gynecology, 1500 6th Avenue South, CRWH 379, Birmingham, AL 35233-1602.

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