HUMAN CHORIONIC GONADOTROPIN (HcG) VS MAGNESIUM SULPHATE (MgSo4) AS A TOCOLYTIC AGENT- A RANDOMIZED CONTROLLED TRIAL

Preterm labor is defined as regular contractions of the uterus resulting in changes in the cervix (effacement and dilatation) that start before 37 weeks of pregnancy. (1) Although preterm labor constitutes only 10% of total labors, yet 70% of infant's mortality is related to prematurity. It is therefore one of the international indices in assessment of health condition worldwide. Factors that increase the risk of preterm birth include history of previous preterm birth, short cervix, short time between pregnancies, teenage pregnancy, history of certain types of surgery on the uterus or cervix, certain pregnancy complications, such as multiple pregnancy and vaginal bleeding and lifestyle factors such as low pre-pregnancy weight, smoking during pregnancy, and substance abuse during pregnancy.

Preterm labor can be diagnosed clinically only when changes in the cervix are found after pelvic examination along with contractions also may be monitored. A transvaginal ultrasound exam may be done to measure the length of your cervix. Tocolytics are drugs used to delay delivery for a short time (up to 48 hours). They may allow time for corticosteroids or magnesium sulfate to be given or for you to be transferred to a hospital that offers specialized care for preterm infants. (1,2) Tocolytic agents are β- HCG, MgSO4, nifedipine, β-agonists(salbutamol) and atosiban. Use of salbutamol is of limited use because of many cardiovascular complications i.e., ventricular arrythmia, hypertension and hyperglycemia while atosiban is expensive and not available in Pakistan.

Human Chorionic Gonadotropin (H.C.G.) is a heterodimeric glycoprotein produced primarily in the placenta and has multiple endocrines, paracrine and immunoregulatory actions. (3) The importance of H.C.G. in maintenance of early pregnancy has been widely accepted, reports have highlighted a potential role of H.C.G. in maintaining uterine quiescence in the third trimester. H.C.G. exerts a potent concentration dependent inhibitory effect on human myometrial contractions. (4) Recent data suggests that H.C.G. might have a role as an endogenous tocolytic agent in normal pregnancy. A significant decrease in serum H.C.G. level was found 2-3 weeks before the spontaneous onset of labour. This might contribute to increasing the contractility in the uterine muscle and gradually initiating the onset of labour. (5) Following I.M. injection, peak concentration of H.C.G. occurs about 6 hrs after a dose. It is distributed primarily to gonads. Blood concentration declines in a biphasic manner, with a half-life between about 6 and 11 hrs and 23 to 38 hrs respectively. About 10 to 12% of an IM dose is excreted in urine within 24 hours. (6)