PHOSPHORYLATED INSULIN LIKE GROWTH FACTOR-BINDING PROTEIN-1 AND TRANSVAGINAL ULTRASONOGRAPHIC CERVICAL LENGTH PREDICTING SPONTANEOUS PRETERM DELIVERY IN SUSCEPTIBLE ASYMPTOMATIC PATIENTS
Preterm births are common. A substantial maternal morbidity accompanies preterm delivery as well as the morbidity associated with prolonged neonatal intensive care. Long-term neurological problems are more difficult to evaluate. Apart from the human cost, the financial cost of providing inpatient care for preterm babies and providing support in cases of lifelong handicap is great. Despite the fact that researchers have evaluated asymptomatic cervical changes that may presage and thus predict preterm labor, and also the knowledge that choriodecidual disruption (releasing phIGFBP-1 amongst other markers) occurs prior to preterm delivery, there is still no standard protocol on the prediction of preterm delivery. In addition, no similar study using phosphorylated insulin-like growth factor binding protein-1 (phIGFBP-1) and cervical length has been done in Nigeria as predictors of preterm delivery. In fact, worldwide, only ten peer-reviewed publications spanning a decade, have reported results of observational studies on phIGFBP-1.
This study therefore aims at determining whether phIGFBP-1 and transvaginal cervical length assessment, alone or in combination, are useful in the prediction of preterm delivery in our environment.
SUBJECTS AND METHODS
The study was an analytical prospective cohort study to be conducted at the antenatal clinic, obstetrics and labour wards of Ahmadu Bello University Teaching Hospital, Zaria where consecutive asymptomatic antenatal clients at risk for preterm delivery were recruited from 22weeks gestation, their sociodemographic characteristics and reproductive profile obtained and the cervical length estimation done using transvaginal
ultrasound. At 30weeks gestation, phosphorylated insulin-like growth factor-binding protein-1 (phIGFBP-1) was assessed from cervical secretions using the Actim Partus bedside test kit and all information entered into a proforma. Patients were followed up till delivery and gestational age at delivery noted. The ability of the tests, singly and in combination, to correctly predict preterm delivery in asymptomatic susceptible patients was determined statistically.
A total of eighty-four clients were used for the final analysis. The participants, mainly Hausa housewives had a mean age of 28.74years. The incidence of preterm delivery among these asymptomatic susceptible patients was 193/1000. Commonest risk factor for preterm delivery was maternal age less than 18 or greater than 35 but a history suggestive of bacterial vaginosis was the significant risk factor. Term delivery occurred in 19.3% of these women at an average gestational age of 38.6weeks. The mean cervical length at 22- 24 weeks in this study was 33.71± 9.61mm. Majority of women with a positive
phIGFBP-1 (82.1%) had term deliveries and similarly, majority of women with short cervices ≤ 25mm had term deliveries, with a relative risk of 0.8 and 0.83 respectively. Both tests did not significantly predict the occurrence of preterm delivery. The sensitivity, specificity, positive predictive value, and negative predictive values for cervical length and phIGFBP-1 are 18.8%, 77.6%, 16.7%, 80% and 62.5%, 31.3%, 17.9%, 77.8% (p values >0.05). the measure of agreement of both tests using the kappa statistic was 0.071.
Predicting preterm delivery still remains a dilemma to the obstetrician. Efforts should be geared towards prompt and adequate prevention in symptomatic patients and management when it occurs. Cervical length measurement at 22-24weeks and use of phIGFBP-1 at 30weeks did not predict spontaneous preterm delivery in susceptible asymptomatic women in our environment.
Further studies should be done with a larger sample size. Findings of studies done in other parts of the world should not always be extrapolated to women in our environment because there may be some differences due to genetic predisposition and lifestyle.