When an egg is fertilized, the surrounding layer (corpus luteum) begins producing progesterone. Once developed, the placenta will produce progesterone.
After the fertilized egg implants in the uterine lining (about 10 days after fertilization), it develops small projections that will become the placenta. These begin to produce estrogen, the other hormone of pregnancy.
The increases of progesterone and estrogen begin a chain of events that help support your baby. You may begin to notice some of these pregnancy symptoms before you miss a period or have a positive pregnancy test.
Possible Pregnancy Symptoms
Several changes in your breasts can begin as early as two weeks after fertilization. You may find your breasts sore or tender to the touch. They may feel fuller or heavy. The skin on the areola may darken.
Your body is creating more waste products as your baby begins to grow, and these waste products must be excreted as urine. Not only is the amount of urine increased, but the bladder becomes compressed between the pelvis and the uterus as the uterus grows. These factors lead to an increased urgency and frequency of urination.
Because of the increased demands on your body's energy stores during pregnancy, you may feel more tired than usual.
Your uterus will be small enough to fit inside your pelvis until about the 12th week of pregnancy, so an increased abdomen size is not normal in early pregnancy. However, some women do experience bloating which may be caused by progesterone slowing down the digestive system.
Some women experience nausea or vomiting during pregnancy. This may be related to the slowing of the digestive system or the increased difficulty in maintaining blood sugar levels when pregnant.
Generally during pregnancy you should not have a menstrual flow. Your regular monthly bleeding is the shedding of the lining intended to support a baby should an egg be fertilized. Because an egg is fertilized, it will produce progesterone which prevents the uterus from contracting so the lining is not shed. Some women do experience a yellowish vaginal discharge, spotting or a small flow around the time they would expect their period. This is normal bleeding caused by the fertilized egg implanting in the uterine lining.
One of the signs caregivers look for to confirm pregnancy is a softened cervix. Your cervix is the opening of the uterus which drops into the vaginal canal. You can find it by feeling deep inside on the upper wall of the vagina, however if you have not been doing cervical mucus checks as part of natural family planning, you will not be able to recognize a change in your cervix.