This is a prospective observational study. Eligible women undergo ART treatment in our centre will be recruited for the study and each woman will only be included in the study once. Informed written consent will be obtained. Blood serum for hCG level is performed 14 days after the embryo transfer i.e. week 4. If the serum hCG level is \>10IU/L, the women are considered pregnant and blood will be saved and checked for kisspeptin level, Another blood test is repeated 1 week later i.e. week 5. A transvaginal ultrasound and blood test will be performed 1 week later i.e. week 6 to confirm the fetal viability and the number of gestational sacs and locate the pregnancy. Blood for hCG and kisspeptin levels are checked at weeks, 4, 5 and 6. Ultrasound will be performed at gestational 8 weeks and 11 weeks. They will be referred for antenatal care when the pregnancy is confirmed on-going at 11 weeks. The purpose is to determine whether serum kisspeptin level in women who conceive in IVF is associated with an increased risk in first trimester miscarriage and compare with serum hCG level in the prediction of the first trimester miscarriage.