Background:
The impact of STD on birth has not been fully assessed.

Objective:
To assess the impact of STD on birth outcomes by matching the Massachusetts (MA) STD and birth registries, with a hypothesis that STD during pregnancy would have a significant effect.

Method:
The MA registry of births to mothers ≤ 25 y.o., 1996-2000 was matched with the MA STD surveillance database. Multiple births were excluded. Neonatal mortality, low birth weight ( < 2,500 g), premature birth ( < 37 weeks), and neonatal stress (Apgar score at 1 minute < 4) were indicators of negative birth outcome.

Result:
66,173 births and 39,067 female STD cases were identified. 7,370 mothers had STD reported with onset prior to labor, with 2,954 (40%) of them during pregnancy. The incidence of reported STD during pregnancy was 5.8% among teens (15-19 y.o.) and 2.7% among those 20-25 y.o, 3.6% for the total. Teen pregnancy (p<0.0001, OR 1.20, 95% C.I. 1.14–1.27) and STD history ( p<0.0001, OR 1.31, 95% C.I. 1.20–1.43) correlated with premature birth, and the effects were additive. Teen pregnancy and STD history also correlated with low birth weight, (p<0.0001, OR 1.44, 95% C.I. 1.35–1.55 and p<0.0001, OR 1.32, 95% C.I. 1.17–1.49, respectively) and the effects were also additive. Teen pregnancy, but not STD history was associated with neonatal stress (p<0.0002, OR 1.22, 95% C.I. 1.10–1.35).

Conclusion:
This study used statewide birth and STD registries applying a reliable matching algorithm. There was a significant association of STD during pregnancy with premature birth and low birth weight, but the impact of STD on birth was not as large as expected. A possible reason for the limited impact of STD is effective screening in prenatal care leading to effective treatment of STD prior to labor.

Implications:
Since many other factors also affect birth. Further study including social-economic characteristics is suggested.