During the first trimester, your body undergoes many changes. Hormonal changes affect almost every organ system in your body. These changes can trigger symptoms even in the very first weeks of pregnancy. Your period stopping is a clear sign that you are pregnant. Other changes may include:

• Extreme tiredness
• Tender, swollen breasts. Your nipples might also stick out.
• Upset stomach with or without throwing up. See morning sickness.
• Cravings or distaste for certain foods
• Mood swings
• Constipation (trouble having bowel movements)
• Need to urinate more often
• Headache
• Heartburn
• Weight gain or loss

As your body changes, you might need to make changes to your daily routine, such as going to bed earlier or eating frequent, small meals. Eating healthy is also important. You should discuss dietary needs including prenatal vitamins, iron and water with your physician. Fortunately, most of these discomforts will go away as your pregnancy progresses. Some women might not feel any discomfort at all. If you have been pregnant before, you might feel differently this time around. Just as each woman is different, so is each pregnancy.

First trimester facts

• You may not gain much weight
• Your due date is calculated 40 weeks from the day of your last period, not the day you conceived.
• Your sense of smell may become much stronger.
• You probably won’t look pregnant.

First trimester screen

The first trimester screen, or nuchal translucency screen, is a screening test done at 11 to 14 weeks to detect higher risk of:

• Chromosomal disorders, including Downsyndrome and Trisomy 18
• Other problems, such as heart defects

This test involves both a blood test and an ultrasound exam called nuchal translucency screening. The blood test measures the levels of certain substances in the mother’s blood. The ultrasound exam measures the thickness at the back of the baby’s neck. This information, combined with the mother’s age, helps doctors determine risk to the fetus.

There have not been any risks or side effects with the first trimester screen, but there is a 5 percent false positive rate. Therefore, there is a chance that the baby will be normal even if abnormal results were found.

Your doctor may suggest other tests depending on the results of the screen.