Some women know from the moment of conception. Others know from some secret signal they or their husbands sense or become aware of. Still others don't have a clue until their tummies bulge and their periods finally stop! We are talking about the very first signs of pregnancy: those tiny clues your body sends that are an indication of things to come.

For some women, it's physical.

Shelley Divnich Haggert, a mother of three from Windsor, Canada, knew exactly when she became pregnant – at least after the first one.

"It's the oddest thing," says Divnich Haggert. "My feet get hot from almost day one. I can't stand having socks, blankets or anything else on them."

For others it's emotional.

"The biggest sign came Thanksgiving weekend," says Trina Lambert, a mother of three from Englewood, Colo. "I was working on my Christmas cards and was addressing and stamping the envelopes. I had out my inexpensive return address labels. When I looked up again, my dog had grabbed them and spread several torn labels around the floor. I burst into tears over this!"

It only took Lambert a minute to realize it wasn't that big of a deal, but she wondered why she reacted so strongly. When she missed her period the next week she took a pregnancy test and sure enough, she discovered she was about 4 weeks pregnant.

"I think many women know they are pregnant before missing the period because most women have a very innate sense of their body and recognize when something has changed, especially as it relates to pregnancy," says Dr. Fink. "Early pregnancy is a time when the organs are developing, and the embryo can be most prone to damage from things a mother might do if she was unaware. Perhaps one of the reasons our species perpetuates is because moms have a subtle internal alarm that sounds when pregnancy occurs and causes her to alter her behavior."

"Hormones of pregnancy cause a 'heavy sensation' in the breasts that often becomes outright breast tenderness or soreness," says Dr. Fink. "I believe breast changes are one of the earlier signs because the breasts are so very sensitive to the effects of hormones."

Dr. Fink says only the lining of the uterus is more sensitive – but the uterine lining is not something most women can feel or otherwise sense. The ductal and support systems of the breast start to make changes from very early in pregnancy in preparation for the milk-making job to come.

Because the glandular portion of the breast becomes enlarged and the surrounding fatty tissue retains fluid, breast enlargement is also a feature of early pregnancy.

"Depending on how you feel about your breasts, this part of pregnancy can either be cause for celebration or a real bummer," says Dr. Fink. "Your bra size may go up a couple of sizes very quickly. Breast tenderness and sensitivity can sometimes be very uncomfortable but passes in most women by about 14 weeks gestation. Wearing a sports bra is the best treatment measure."

According to Dr. Fink, pregnancy hormones also cause changes in the nipples. They usually become darker, usually larger, and the areola becomes wider. Dark blue veins that might not have been visible before can suddenly be seen through the skin.

Though breast tenderness is common, not every woman experiences it. Dr. Fink cautions that every woman and pregnancy is different and the early signs of pregnancy vary from woman to woman and from pregnancy to pregnancy.

Dr. Lauri Grossman, a chiropractor and homeopathic physician in private practice in New York, says breast tenderness isn't the only early sign of pregnancy.

"Digestive changes can occur as well," says Dr. Grossman. "Sometimes, they are mild; other times they are dramatic ranging from mild bloating, belching, constipation, passing of gas, increased appetite and changes in desire for certain foods to debilitating nausea and food and smell intolerances."

"Women can feel happy, excited and full of anticipation at the thought of being pregnant," says Dr. Grossman. "This can shift to feelings of doubt, fear and anxiety about being pregnant and having a baby. As different issues arise, such as those related to finances, childcare, sexual intimacy or the growing family, moods can shift quickly."

Dr. Grossman suggests women dealing with these mood swings and some of the other early symptoms of pregnancy should talk about how they are feeling. "Expressing these emotions and processing them in an open dialogue can ease the stress associated with changing moods," says Dr. Grossman. "Relaxation exercises including meditation and deep breathing exercises can lessen this problem as well."

Whether you know you are pregnant from the moment of conception or you find out some time later by an offbeat series of symptoms, enjoy this part of your pregnancy. It is a unique part of a unique pregnancy and cause for joyous celebration – no matter what symptoms you are experiencing!

For at list of symptoms, click here.