The first day of your last period is week number one of pregnancy. Let's see how it works. What's happening to you? Your pregnancy cycle starts from the first day of your last menstrual period. Menstruation isn't just about cramps, cravings and mood swings — your body is preparing for ovulation, where an egg is released in the hope of fertilisation from an eager sperm. As your body produces hormones (oestrogen and progesterone), your womb prepares to support a fertilised egg by shedding and replacing its lining with nutrient-rich tissue. It's normal to feel moody during your period. Your hormones are surging as your body prepares itself for fertilisation. Around day 14, ovulation will occur and the chance of pregnancy is at its peak. By Associate Professor TAN Thiam Chye Head & Senior Consultant, Dr TAN Shu Qi Senior O&G Resident, Department of Obstetrics and Gynaecology, KK Women's and Children's HospitalCopyright © 2016 HealthHub.sg. All rights reserved.