One of the most important reasons to see your obstetrician regularly in pregnancy is for evaluation and prevention of potential preterm deliveries-those deliveries before 37 weeks estimated gestation age. Almost 50% of all spontaneous preterm births lead to fetal demise. This includes births following preterm labor, preterm rupture of membranes or an insufficiently strong cervix. Infants born prematurely have increased risk of mortality and chronic illness throughout their childhood, especially early on.
An obstetrician might recommend preterm delivery for maternal or fetal indications-the demise rate is not as high as in spontaneous preterm deliveries.
If you have had a previous preterm delivery, you have almost a two-times greater risk of having a second premature delivery. Another indication of preterm delivery is a shortened cervix, as detected on ultrasound – this is the reason many of us like to get early third trimester transvaginal ultrasound. Certain medical and gynecologic histories, such a history of cervical or uterine surgery, can also increase the risk of preterm delivery. Lastly certain behavioral factors, such as smoking cigarettes or using non-prescribed drugs, can increase the risk of preterm labor.
While we often consider a LEEP procedure or a cervical cone procedure a risk factor for preterm labor, it may be the environmental and behavioral factors leading to cervical dysplasia that increases the risk. Nor is it clear that multiple cervical dilations, such as with terminations of pregnancy, increase the risk factors, although multiple procedure can increase the risk of chronic microbial colonization of the uterine lining. This leads to chronic endometritis, which will increase the risk of preterm delivery.
Women with a history of unexplained vaginal bleeding, frequent urinary tract infections, STDs and poor oral health are also at risk of preterm delivery. Low maternal pre-pregnancy weight, smoking, substance abuse and recent previous pregnancy, less than one year also have an impact on preterm labor rates.
There are a few modalities we can use to assess the risk of preterm labor. As mentioned before, transvaginal ultrasound to determine cervical length is now often employed by my obstetricians. Fetal fibronectin testing is another way to determine if the risk of preterm delivery has increased. Looking for and treating vaginal or cervical infections, such as bacterial vaginosis, chlamydia and gonorrhea can reduce the possibility of preterm labor. The best way, still, is face-to-face contact, history taking and examinations.
The bottom line is this: your obstetrician can assess, through history, complaints, labs and examinations your risks for preterm labor and help prevent preterm delivery. Although this will not 100% guarantee no preterm labor problems, we are there to prevent situations as well as deal with current problems. For this to happen you must come to your regularly scheduled visits.