The first 12 weeks of your pregnancy is time of important changes to your body and developmental stages for your baby. You will probably feel excited, exhausted and just pregnant. During the first trimester you may experience fatigue and morning sickness. You mood may swing between being happy and sad, joyous to anxious, all within the space of 30 minutes. By the second month you may experience breast tenderness, fullness in your abdomen and frequency of urination. By late first trimester you may start to show a little baby bump, the nausea will start to improve and you will start to feel more normal.
You should gain about 1 pound per month. The old adage eating for two is false, you only need an additional 350 to 450 extra calories per day.
In the first trimester your baby settles into your uterus for the pregnancy. During weeks 3 through 8 called the embryonic stage the major organs are developing. The brain and spine start to form (importance of prenatal vitamins with folic acid), and the heart start to pump blood. Your baby is about 1 inch long. During weeks 9 through 12 your baby’s (fetus) external sex organs start to form, fingers and toes develop, internal organs like stomach, lungs and intestines take shape. Your baby begins to move and is 1 to 3 inches long weighing about 1 ounce.
During your first obstetrical appointment, your doctor will conduct a medical history, physical exam, obtain labs, discuss genetic testing options, review basic information regarding diet/exercise/healthy lifestyle, and establish a due date.
Your due date is based on your last menstrual period from which we add 40 weeks (280 days), this is usually correlated with and early ultrasound especially if your last period was unsure or irregular.
In regards to labs testing we usually order a blood count to evaluate for anemia, screen for infections such as syphilis, gonorrhea, chlamydia and hepatitis. We usually check your immune status to rubella and chicken pox. We may screen early for diabetes based on your history. We will also review the genetic testing options.
Genetic testing evaluates for both chromosome problems and structural disorders. Chromosomes are building blocks in our cells that contain our genetic information. We have 46 chromosomes which come in pairs with each person have 23 pairs with one being the sex chromosome responsible for determining if baby is boy or girl. Genetic screening can detect missing or extra chromosomes. Down syndrome results from extra chromosome number 21 resulting in specific physical features and cognitive impairment. The level of impairment can vary but most people with Down syndrome can read and write and are able to live fulfilling lives. The incident of genetic disorders increase as the mother age increases. The most recent development in genetic screening is the NIPT test (noninvasive prenatal testing). NIPT is a blood drawl that measures cell free DNA from the placenta. The DNA is used to evaluate for chromosome abnormalities especially Down syndrome, trisomy 13 and 18 and sex chromosome disorders. This is a screening test versus a diagnostic test (amniocentesis and Chorionic villus sampling). NIPT is done as early as 10 weeks, it can also determine fetal sex but cannot detect birth defects (spina bifida) so it should be combined with a test called alpha fetal protein which is done between 15 and 20 weeks. Early detection allows time to a make decision regarding pregnancy. There is no cure for chromosome problems and the decision of what to do with the information is very personal. Other genetic screening may be offered based on your ethnic or racial background and includes testing for cystic fibrosis, sickle cell disease, thalassemia, Tay-Sachs disease, Canavan disease, familial dysautonomia and fragile X syndrome.
Joseph Stalfire, M.D., FACOG