Some women have no pregnancy symptoms at week 1, while others may experience symptoms such as fatigue, breast tenderness, and mild cramping. Normally medical professionals measure pregnancy week 1 from the first day of a woman’s last menstrual period. Although a woman is not actually pregnant at this point, counting week 1 from the last menstrual period can help determine a woman’s estimated pregnancy due date. Ideally we would refer to pregnancy week 1 as starting a week after conception, meaning the literal first week of pregnancy. A missed menstrual period is often the primary symptom of early pregnancy. Conception, or fertilization, occurs when the ovary releases an egg (ovulation), and a sperm fertilizes it. This can happen about 14 days after the menstrual cycle starts, according to March of Dimes. According to Planned Parenthood, implantation begins about 6 to 7 days after conception. This is when the fertilized egg attaches to the lining of the uterus. This movement of the egg may break down blood vessels within the uterus wall, which may cause light bleeding and cramping.

Bleeding

Implantation Bleeding is an early prediction of pregnancy. It is not like a menstrual period. Instead, it is light bleeding that may involve a single spot of blood or a small amount of pink discharge. The spotting may last for a few hours, or it may last for a few days.

Cramping

Women may also feel mild cramping as the embryo attaches to the uterus wall. Women may feel these cramps in the abdomen, pelvis, or low back area. The cramping may feel like a pulling, tingling, or pricking sensation. Some women experience only a few minor cramps, while others may feel occasional discomfort that comes and goes over a few days.