The Three Trimesters
Pregnancy has three trimesters, each of which is marked by specific fetal developments. A pregnancy is considered full-term at 40 weeks; infants delivered before the end of week 37 are considered premature. Premature infants may have problems with their growth and development, as well as difficulties in breathing and digesting.
First Trimester (0 to 13 Weeks)
The first trimester is the most crucial to your baby's development. During this period, your baby's body structure and organ systems develop. Most miscarriages and birth defects occur during this period.
Your body also undergoes major changes during the first trimester. These changes often cause a variety of symptoms, including nausea, fatigue, breast tenderness and frequent urination. Although these are common pregnancy symptoms, every woman has a different experience. For example, while some may experience an increased energy level during this period, others may feel very tired and emotional.
Second Trimester (14 to 26 Weeks)
The second trimester of pregnancy is often called the "golden period" because many of the unpleasant effects of early pregnancy disappear. During the second trimester, you're likely to experience decreased nausea, better sleep patterns and an increased energy level. However, you may experience a whole new set of symptoms, such as back pain, abdominal pain, leg cramps, constipation and heartburn.
Somewhere between 16 weeks and 20 weeks, you may feel your baby's first fluttering movements.
Third Trimester (27 to 40 Weeks)
You have now reached your final stretch of pregnancy and are probably very excited and anxious for the birth of your baby. Some of the physical symptoms you may experience during this period include shortness of breath, hemorrhoids, urinary incontinence, varicose veins and sleeping problems. Many of these symptoms arise from the increase in the size of your uterus, which expands from approximately 2 ounces before pregnancy to 2.5 pounds at the time of birth.
Prenatal Care
Expert prenatal care ensures that both you and your baby are as healthy as possible throughout your pregnancy.
If you think you're pregnant, contact your doctor to make an appointment and establish your prenatal care schedule. Many factors determine the number of visits you'll have, including your personal health and your doctor's preference.
At prenatal visits, we test you and your baby to identify any potential risks, treat any complications, and monitor your baby's growth and development. Additional prenatal care may be needed if you have preexisting medical conditions, such as diabetes, or if complications arise during your pregnancy.
If your pregnancy is going well, visits are planned around key pregnancy developments and tests. Visits are also a time for your doctor to give you important information as your pregnancy progresses and help you prepare for giving birth.
Here's a guide to the most common prenatal tests, including when they happen and what you can expect.
Genetic carrier screening
Timing: Before or during pregnancy
How it works: A blood test is done to see whether you're a carrier of a genetic change that could raise your baby's risk for a genetic condition. Two conditions commonly screened for are cystic fibrosisand spinal muscular atrophy.
California Prenatal Screening Program (CA PNS)
CA PNS screening is a combination of these two blood tests, performed at different stages of pregnancy:
- Cell-free DNA screening (also called noninvasive prenatal testing or NIPT) is done at 10 weeks of pregnancy or later to determine a baby's risk for Down syndromeand two other syndromes, trisomy 18 and trisomy 13. It can also predict the sex of your baby.
- A maternal serum alpha-fetoprotein (MASFP) screening is done between 15 and 21 weeks of pregnancy to assess the risk for abnormalities of the spine (neural tube defects) or abdomen (abdominal wall defects).
Nuchal translucency test
Timing: Usually between 12 and 14 weeks of pregnancy, at the first trimester screening
How it works: An abdominal ultrasound measures the amount of fluid behind the baby's neck to look for certain genetic conditions as well as structural problems, such as heart defects. Extra fluid in that area indicates a higher risk of chromosome abnormalities, birth defects and genetic conditions.
Chorionic villus sampling (CVS)
Timing: Usually between 10 and 13 weeks of pregnancy
How it works: A small sample of the placenta is taken and sent for testing to identify any chromosomal or genetic disorders. (Not everyone who is pregnant chooses to have CVS.)
Amniocentesis
Timing: Usually between 16 and 22 weeks of pregnancy
How it works: The doctor takes a small sample of the amniotic fluid surrounding your baby. Genetic testing of that fluid can identify chromosomal or genetic disorders as well as neural tube defects. (Not everyone who is pregnant chooses to have amniocentesis.)
Early fetal anatomy examination
Timing: Usually between 12 and 14 weeks of pregnancy
How it works: Like the level 2 anatomy ultrasound done in the second trimester, the first-trimester ultrasound examines many physical aspects of your baby's body and includes additional imaging, such as the evaluation done in a nuchal translucency ultrasound. It's usually recommended for high-risk patients, such as those who are carrying a baby with a suspected abnormality, had high-risk findings on a genetic screening test, or had a previous pregnancy with fetal abnormalities.
Anatomy ultrasound (level 2)
Timing: Around 20 weeks of pregnancy
How it works: An "anatomic survey" examines many aspects of your baby's body, including the heart, brain, spine, limbs and certain other organs. The anatomy ultrasound visit also includes an assessment of the placenta and of your uterus and cervix.
Glucose tolerance test
Timing: Usually between 24 and 28 weeks of pregnancy
How it works: This test measures the level of sugar (glucose) in your blood. An abnormally high blood sugar level may be a sign of gestational diabetes, a type of diabetes that can develop during pregnancy and requires monitoring.
Fetal monitoring
How it works: Your doctor may want to monitor your baby's heart rate (using an ultrasound transducer) and measure uterine contractions (using a device called a toco transducer).
Group B strep testing
How it works: Doctors routinely take a sample from your vagin* and rectum during pregnancy to test for group B streptococcus ("group B strep") bacteria.
Group B strep bacteria can cause infections during pregnancy and lead to complications and even death for a newborn if transmitted during delivery. Fortunately, the infection can easily be treated with antibiotics during pregnancy.
Labor and Delivery
Labor is a series of progressive and continuous contractions of the uterus that help the cervix to open and thin, allowing the baby to travel through the birth canal. Labor usually starts within two weeks before or after your estimated delivery date. However, this can vary widely.
Labor and delivery are hard work and involve some discomfort. The level of discomfort experienced during childbirth varies from woman to woman and from pregnancy to pregnancy. Each woman chooses a different way to experience her birth — some prefer to go through it without medication, while others choose to have medication or anesthesia. Many decide to "see how it goes" and make choices as their labor unfolds.
We offer a spectrum of options for managing your pain during labor and delivery. You will be assigned to your own nurse during your stay in the birthing suite. He or she will help keep you comfortable and guide you through non-drug approaches to pain management, such as whirlpool soaks and position changes.
Pain Management
Non-Medical Approaches for Labor and vagin*l Birth
The Birth Center rooms provide a number of options for comfort during labor including space to move around, tubs for soaking, rocking chairs and beds that convert into different positions.
Relaxation and breathing techniques ease the discomfort for many, as does the presence of family and friends and the support of health care providers. Comfort measures can be learned from classes, books or videos available through UCSF's Great Expectations Pregnancy Program.
Medical Approaches for Labor and vagin*l Birth
- Narcotic Injections of a narcotic can be given intravenously (through an IV) during labor. The narcotic works quickly and can be given every hour during labor. However, it is not given immediately before delivery to ensure that the effects will have worn off before the baby is born. For some women, this medication takes the edge off and allows them to rest and relax between contractions.
- Nitrous oxide gas This is the same gas that is used at the dentist, and can be inhaled during contractions through a mask you hold. The gas can lessen but not eliminate the pain of labor. The effect occurs only while the gas is being inhaled and disappears rapidly when the mask is removed. It can be used through delivery.
- Epidural anesthesia An epidural offers the most complete pain relief during labor and birth. A tiny tube or catheter is placed through a needle into a space (the "epidural space") outside the spinal cord sac in the lower back. The needle is removed and the tubing is taped in place. Similar to an IV, medication is given continuously through the tube during labor and birth. The medication blocks the pain of contractions. Because of the numbness produced by the epidural, a woman with an epidural cannot get out of bed. Most women take the opportunity to get some rest. A "walking epidural" — also called a "combined spinal-epidural" — is a technique that allows a woman to continue to move around while receiving a lighter form of medication.
Our anesthesiologists are available to the Birth Center 24 hours a day. The anesthesiologist on-call meets every woman who is admitted in labor regardless of whether she is planning anesthesia for her birth. The purpose of this visit is two-fold: To learn of any medical problems you may have in the unlikely event of an emergency, and to answer any questions you may have about the pros and cons of medical approaches to pain relief during labor.
Caesarean Birth
When a Caesarean is Needed
While most women will have a vagin*l delivery, some may need abdominal surgery referred to as Caesarean section. Most often women have a Caesarean birth when labor does not progress — the cervix does not completely dilate or the baby cannot be pushed out — over a long period of time. It is a decision made by the woman and her doctor when both feel everything else has been tried and this is the only alternative.
Sometimes a Caesarean birth is planned. Situations that might require a scheduled Caesarean include:
- Breech position
- Previous Caesarean section
- Placenta previa, when the placenta is covering the cervix
Rarely, Caesarean birth is due to an emergency situation that endangers the woman's or her baby's health. In these situations, there is no time to wait for the regular process of labor and the decision to perform a Caesarean section must be made very quickly. Indications for an emergency Caesarean may include:
- Maternal bleeding
- The baby being in distress
Anesthesia for Caesarean Section
For a planned or non-emergency Caesarean, an epidural or spinal anesthesia is the anesthesia of choice. This allows the woman to be awake and able to see her baby immediately after birth. In an emergency situation, the woman would be put to sleep using general anesthesia. This is the fastest anesthesia to administer when time is of the essence.
If the woman is awake, a support person can be with her for the birth. If general anesthesia is used and the woman is asleep, support people need to wait in the labor room or waiting room until the surgery is completed.
Caesarean Procedure and Recovery
Most often, the doctor will make a low transverse incision — a "bikini cut" — both on the skin, just above the pubic hair, and on the uterus itself. This is a preferable cut for both comfort and recovery. Occasionally an "up and down" or vertical incision is made on the skin, uterus, or both. This is a faster cut and may be used in an emergency. The size and position of your baby also may determine the need for this kind of incision.
Recovery from surgery takes longer than recovery from a vagin*l birth. Usually it requires an extra night or two in the hospital, for a total of three to four nights, and more help at home in the first few weeks.
Many women choose to attempt a vagin*l birth after Caesarean, called VBAC, and many will succeed. Every woman who has had a Caesarean will need to discuss the subject of VBAC with her provider. Many factors — including the reason for the Caesarean, the type of incision and the number of prior Caesareans — will influence the safety of VBAC.
Birth Plans
You will be provided with a Birth Plan, a form asking about your preferences for delivery. This promotes communication with your health care provider and helps them meet your individual needs. You will complete your Birth Plan and discuss it with your health care provider at your 34 to 36 week visit.
Make photocopies of your Birth Plan. Give one to your health care provider to put in your medical record, and bring one with you when you come to the hospital in labor.
