Oxford Luteal Dysfunction and Placental Insufficiency Study

High blood pressure (BP) affects approximately 1 in 10 pregnancies. About half of women with high blood pressure in pregnancy develop a serious complication called preeclampsia, which kills over 70,000 women and 500,000 babies every year worldwide. Despite its devastating impact, scientists know little about preeclampsia prevention or treatment. Research has shown that preeclampsia results mainly from an abnormal attachment of the placenta to the lining of the womb. In the first 8 weeks of pregnancy, placental attachment depends on the release of hormones (for example, progesterone) by a gland in the ovary called the corpus luteum. Low blood levels of progesterone in early pregnancy are associated with a reduced chance of having a live baby and higher risk of miscarriage. Giving progesterone to women at risk of miscarriage in early pregnancy reduces their chance of developing preeclampsia by nearly 40%. These results highlight the crucial role of the corpus luteum in normal pregnancy, but there is a need for high-quality studies to identify women whose corpus luteum may be defective. Giving these women medicines to treat corpus luteal defects may lead to normal attachment of the placenta, reducing the risk of pregnancy complications such as preeclampsia. The investigators propose a study that will investigate whether ultrasound features of the corpus luteum and blood and urine levels of corpus luteal hormones may predict preeclampsia.