Objective To evaluate the relationship between interleukin (IL)-18 in cervical mucus and amniotic fluid and microbial invasion of amniotic fluid, preterm delivery and intra-amniotic inflammation in women in preterm labour, with preterm prelabour rupture of membranes and at term.
Design A prospective follow up study.
Setting Sahlgrenska University Hospital, Göteborg, Sweden.
Sample Women with singleton pregnancies (<34 weeks) presenting with preterm labour (n= 87) or preterm prelabour rupture of membranes (n= 47) and women, not in labour, at term (n= 28).
Methods Amniotic fluid was retrieved transabdominally. Cervical mucus was taken from the uterine cervix of women in preterm labour and at term. IL-18 was analysed with enzyme-linked immunosorbent assay.
Main outcome measures IL-18 in relation to microbial invasion of the amniotic fluid, delivery within seven days or <34 weeks of gestation and intra-amniotic inflammation.
Results The levels of IL-18 in cervical mucus and amniotic fluid were higher in women with preterm labour than in those not in labour at term. In the preterm labour group, significant associations were found between elevated IL-18 in amniotic fluid and microbial invasion of the amniotic fluid, as well as between delivery within seven days or <34 weeks of gestation and intra-amniotic inflammation. Delivery was delayed longer in the preterm prelabour rupture of membranes subgroup with IL-18 ≥1.0 ng/mL than in that with IL-18 <1.0 ng/mL.
Conclusions In the preterm labour group, high IL-18 in amniotic fluid (but not in the cervix) was associated with microbial invasion of the amniotic fluid, intra-amniotic inflammation and prompt delivery. On the other hand, elevated IL-18 in preterm prelabour rupture of the membranes group correlated with a longer interval to delivery.