During Your First Trimester from UPMC in Central Pa.

A healthy first trimester is crucial to normal fetal development. After you have chosen your physician or midwife, be sure to schedule your first prenatal visit. If you have concerns about any symptoms you may be experiencing, contact your physician right away.

Your First Prenatal Visit

During your first prenatal visit, your physician will take a complete medical history and perform a physical exam. You will also have a first trimester screening, which will include several tests and procedures to assess the initial health of your baby.

Be prepared to answer questions about your personal and family health history. You should also ask questions or discuss any concerns that you have about your pregnancy.

Your Baby's Development

Early in the first trimester your embryo implants itself in the uterine wall, and the following major developments take place:

• A sac filled with amniotic fluid, called the amniotic sac, surrounds your baby to protect it from injury and regulate temperature.
• An organ called the placenta, which is shaped like a flat cake, forms and attaches to your uterine wall with tiny projections called villi. Fetal blood vessels grow from your baby's umbilical cord into the villi, exchanging nourishment with your blood and removing waste products.
• The umbilical cord, which contains two arteries and a vein, connects your baby to your placenta. The umbilical cord carries oxygen and nutrients to your baby and waste products away from your baby.

During the first eight weeks of your pregnancy, your baby is called an embryo. By the end of the first trimester, your embryo will become a fully formed fetus, weighing approximately ½-1 ounce and measuring three to four inches long, on average.

During the first trimester, your baby is most susceptible to damage from substances such as alcohol, drugs and certain medications and from illnesses such as rubella.

Changes to Your Body

Some symptoms of pregnancy continue for several weeks or months, while others are only experienced for a short time. Keep in mind that every woman experiences pregnancy differently. You may experience some or many of the following changes:

• Spotting and cramps a few days after conception as the fertilized egg attaches itself to the wall of your uterus
• Swollen and tender breasts, which prepare your body for breastfeeding
• Frequent urination as your uterus grows and begins to press on your bladder
• Mood swings, irritability and other symptoms similar to those that occur shortly before your menstrual period
• Nausea and sometimes vomiting caused by elevated hormone levels, which is called morning sickness, even though it can occur at any time of day
• Constipation, heartburn and/or indigestion
• Extreme fatigue due to the physical and emotional demands of pregnancy
• A bulge in your abdomen caused by your growing uterus

Carrying Multiples

Although multiples account for only a small percentage of all births (about three percent), the number of women pregnant with twins or multiples is on the rise. According to the National Center for Health Statistics, the twin birth rate has risen by 70 percent since 1980 and as of 2015 is at 32.6 per 1,000 live births. There are several factors that increase your chances of becoming pregnant with multiples, including:

• Heredity. A family history of multiple pregnancies increases your chances of having twins.
• Older age. If you're older than age 30, you have a greater chance of becoming pregnant with twins.
• Race. African-American women are more likely to have twins than any other race. Asian-American women and Native Americans have the lowest rates of twin births.
• Use of ovulation-stimulating medications. Clomiphene citrate and follicle stimulating hormone (FSH) help produce many eggs, which, if fertilized, can result in multiples.
• Assisted reproductive technologies. In vitro fertilization (IVF) and other techniques use ovulation-stimulating medications to produce multiple eggs.
• Twins can be fraternal or identical. Fraternal twins usually occur when more than one egg is fertilized and implants in the uterus, producing boys, girls or a combination of both. Identical twins occur when one egg is fertilized and divides into two embryos, producing two boys or two girls. If you are pregnant with twins, you may experience the following symptoms:
  • A larger-than-expected uterus for the date of your pregnancy
  • Increased morning sickness
  • Increased appetite
  • Excessive weight gain, especially early in pregnancy
  • Feeling fetal movements in different parts of the abdomen at the same time

Being pregnant with multiples, while exciting, can carry increased risks of complications such as preterm labor, premature birth, miscarriage and anemia. Your physician will evaluate your pregnancy and your babies, help you understand what you can expect from the pregnancy and manage any complications that may arise.

Need more information?  

Learn more about Prenatal and Maternity Services at UPMC in central Pa.

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