Preterm delivery

In this issue of Acta Obstetricia et Gynecologica Scandinavica, a number of publications focusing on preterm delivery have been assembled, including proceedings [3, 6–10] from the international meeting ‘Biomarkers and Preterm Delivery’, Middlefart, Denmark, June 5, 2004. I have allowed myself to summarize the conclusions* like this: Prevention of preterm delivery is a major obstetrical challenge, but our management of this challenge has so far been a complete flop: According to European, Australian, and North American databases, the incidences of preterm delivery before 37weeksand32weeksincreasesteadily(1). This isnotonlydue toassisted conception, as increasedpreterm deliveryrateshave been demonstrated also among spontaneous pregnancies. In this issue, the fist optimistic epidemiological report since long publishedshowsthat inSwedenthepretermbirthrate ‘showsa significant decrease beginning in the mid-eighties; this is most evident among singleton births at gestational age of 34–36 weeks. The decrease is evident, despite an increasing contribution of multiple births and increasing maternal age (2)’. The pathophysiology is complex and multifactorial. Since long ago it has been established that intrauterine infections account for approximately one third (3). According to a new hypothesis, these infections are not always ascending but may be caused by pathogens present in the endometrium before conception (4). This very important suggestion may explain why cytokines in cervical fluid are associated with preterm delivery (5). A number of large databases including biological material are now available for future studies on pathophysiology (6). Anyone with good ideas is encouraged to contact the Danish National Birth Cohort. Another pathophysiological factor is the collagen content of the uterine cervix. In humans moving around in an upright position, the ability of this tissue to withstand the 38 weeks load of the pregnancy product is extremely important. It has now been suggested that this collagen can easily be assessed in vivo using a newly developed ‘collascope’ (7). So far, this equipment based on light reflection is not commercially available, but the results are promising. The major achievement, however, is our increased ability to identify women at risk of preterm delivery (1). Based on score systems including history (8), ultrasound visualization of the cervix (9), biomarkers in serum (10), and vagina, (3,5) it is possible to identify a very large percentage of asymptomatic pregnant women, who will deliver preterm. Furthermore, absence of fetal fibronectin in vaginal fluid identifies low-risk patients among women with contractions. These low-risk women might be let off intensive obstetrical care in spite of their symptoms (1). The major frustration is our inability to help women at risk of preterm delivery. So far, social support, antibiotics, sick leave, bed rest, or cervical cerclage (9) seem to be of only limited value. Therefore, much attention has been paid to recent publications on intramuscular injection of 17ahydroxy progesterone demonstrating a reduction of delivery rate before 37 weeks from 55 to 36% (1). The extremely high background risk in this study population, however, warns against uncritical application of this regime on populations with lower risks. Niels Uldbjerg