This clinical trial is focused on studying the effects of the medication dexamethasone in treating a condition known as Congenital Adrenal Hyperplasia (CAH). CAH is a genetic disorder that affects the adrenal glands, which are small glands located on top of the kidneys. These glands produce important hormones, and in CAH, there is a problem with hormone production that can lead to various health issues. The trial will use different doses of dexamethasone, a type of medication known as a glucocorticoid, which is often used to reduce inflammation and suppress the immune system.

The purpose of this study is to determine if a lower dose of dexamethasone is as effective as the higher dose currently used in preventing certain effects of CAH in unborn female babies. Specifically, the study aims to see if the lower dose can prevent prenatal virilization, which is the development of male physical characteristics in female babies before birth. Additionally, the study will look at how the medication affects the weight gain of the mother during pregnancy.

Participants in the study will take dexamethasone in the form of a hard capsule, which is taken orally. The study will compare different doses of the medication, including 0.5mg, 0.21mg, 0.41mg, and 0.15mg, over a period of up to 40 days. Some participants may receive a placebo. The trial will monitor various health outcomes for both the mother and the child, including the closure of the urogenital sinus in the baby and the mother’s weight gain during pregnancy. Safety aspects such as the occurrence of stillbirths, miscarriages, and any side effects in both mothers and children will also be closely observed.