Early Pregnancy Symptoms

Symptom	When It Occurs	What Causes It to Occur During Pregnancy	Other Possible Causes
A missed period	Around the time that your period is due.	Rising levels of progesterone fully suppress your menstrual period.	Jet lag, extreme weight loss or gain, a change in climate, a chronic disease such as diabetes or tuberculosis, severe illness, surgery, shock, bereavement, or other sources of stress.
A lighter-than-average period	Around the time that your period is due.	Your progesterone levels are rising, but they are still not high enough to fully suppress your menstrual period.	May also be experienced by birth control pill users.
A small amount of spotting	Approximately 1 week after conception.	This type of spotting may occur when the fertilized egg implants in the uterine wall about a week after conception has occurred.	May be experienced by users of birth control pills and women with fibroids or infections. Some women routinely experience midcycle spotting.
Abdominal cramping (periodlike cramping in the lower abdomen and pelvis and/or bloating and gassiness)	Around the time that your period is due.	Abdominal cramping may be triggered by the hormonal changes of early pregnancy. Some women describe this cramping as a feeling like their period is about to start.	PMS, constipation, irritable bowel syndrome.
Breast tenderness and enlargement	Breast tenderness can set in as early as a few days after conception; It doesn't typically last beyond the first trimester.	Breast tenderness and enlargement are caused by the hormonal changes of early pregnancy. You may also notice some changes to the appearance of your breasts: the areola may begin to darken and the tiny glands on the areola may begin to enlarge.	Premenstrual syndrome (PMS), excessive caffeine intake, or fibrocystic breast disease.
Morning sickness (a catchall term that is used to describe everything from mild nausea to severe vomiting that can lead to dehydration)	2 to 8 weeks after conception.	Scientists believe that morning sickness is somehow linked to high levels of progesterone and human chorionic gonadotropin (hCG), but they aren't sure of the particular mechanisms involved.	Flu, food poisoning, or other illnesses.
Food aversions and cravings (e.g., a metallic taste in the mouth and/or a craving for certain types of foods)	2 to 8 weeks after conception.	Food aversions and cravings are triggered by the hormonal changes of early pregnancy.	Poor diet, stress, or PMS.
Heightened sense of smell	2 to 8 weeks after conception.	The heightened sense of smell that many pregnant women experience is the result of the hormonal changes of early pregnancy.	Illness.
Increased need to urinate	As early as 2 to 3 weeks after conception.	The increased need to urinate is triggered by increased blood flow intake.	A urinary tract infection, uterine fibroids, or excessive caffeine to the pelvic region and by the production of human chorionic gonadotropin (hCG) during early pregnancy.
Constipation	As early as 2 to 3 weeks after conception	Progesterone relaxes the intestinal muscles, resulting in varying degrees of constipation.	Inadequate intake of high-fiber foods or inadequate consumption of fluids.