Hi and welcome to HCM Strone contain the hormone Progesterone and it is actually vital to a healthy, full term pregnancy. A lack of it can result in a miscarriage or pre-term labor and it is also necessary to support the placental function. Your doctor wants you to use this to help ensure that you can support the pregnancy for the full 9 months. During pregnancy, the normally short cervix lengthens to anywhere between an inch and a half (3.8 centimeters) to a little over two inches long (5 centimeters, as measured by ultrasound). Occasionally a pregnant women have a cervix that measures a bit shorter sometimes as little as a half-inch long. When the cervix is that short, the risk of premature cervical effacement (thinning) and dilation and, therefore, of premature labor does unfortunately rise, as in your wife case. Doctor might order strict bed rest toward the end of her pregnancy and in some cases doctor may perform a fairly simple yet controversial (because its benefits are still uncertain) procedure called a cerclage in which cervix is sewn together with a surgical stitch. Follow doctor advice and i wish her a safe delivery Regards Dr Santosh