An Overview of Pregnancy By Robin Elise Weiss, PhD | Reviewed by Anita Sadaty, MD Updated September 12, 2016 Print So much happens during pregnancy that it's basic definition—the period of time when a human being grows from the combination of genetic material from a single egg and sperm—seems almost too simplistic when you say it aloud. Typically, conception occurs naturally through sexual intercourse. Over the course of about forty weeks, the baby grows and matures from those two cells to a fully developed baby and is born. Pregnancy is divided into three nearly equal trimesters, each with its own challenges and changes for both the pregnant person and baby.A view of baby in utero. Diagnosing PregnancyPregnancy is usually diagnosed via a home pregnancy test. This uses urine to detect the presence human chorionic gonadotropin (hCG). You can take a home pregnancy test from about the time you would expect your period. Once you have a positive pregnancy test, you will make an appointment to see your obstetrician or midwife. Article Tips for How Long to Wait to Take Another Pregnancy Test Article What a Lighter Period May Mean for Your Health He or she may repeat the test or use physical symptoms to diagnose your pregnancy for the medical record. This is when you begin your prenatal care.Prenatal CarePrenatal care encompasses the nine months plus of medical care that you receive from a doctor or a midwife. You will usually see someone once a month for the first two trimesters of pregnancy, every two weeks in the pregnancy weeks 28 through 36, and weekly until the birth of your baby. The goal of prenatal care is to keep you and baby healthy. This includes both screenings and preventative care. This is accomplished through weight checks, listening to your baby’s heartbeat, routine blood work, and more. You may also see other tests:Blood pregnancy testGenetic testingUltrasound examsNon-stress tests (NST)Your practitioner will help you determine which tests are needed for you and your baby in this pregnancy, as it may vary based on many factors. Your practitioner will also work with other medical care providers that you see for other potential issues that you have, for example, if you have another specialist for a chronic condition. They will work together to help get you on the right medications for pregnancy, if needed.First Trimester (Weeks 1 to 13)One of the things that makes the first trimester unique is that it begins with the first day of your menstrual cycle. You may not even be planning to be pregnant at this point, nor will you know that you are pregnant until around the four week mark (at the earliest). So, for at least about a third of this trimester, you diagnose the weeks in the past.From the point of a positive pregnancy test, the pregnant person is aware of the pregnancy, even though it is not evident to the outside world. Article Have Your Period but Still Worried You Might Be Pregnant? Article How Soon Can You Get Pregnant After Giving Birth? Even though you may not be "showing," there is a lot going on inside your body. From those two cells to an embryo with a beating heart, the changes in these first weeks are amazing. Every organ system is beginning to form, as are the baby’s arms, legs, fingers, and toes.You may be feeling the effects of pregnancy starting around the sixth week of pregnancy. This can include a host of things, including:Morning sicknessSore breastsFatigueHeartburnInsomniaYou may also be concerned about the pregnancy and its viability. Miscarriage is most common in this early trimester, with as many as 20 percent of pregnancies ending before the end of the first trimester. Your doctor or midwife can help you determine if there is a threat to your pregnancy. He or she will also help you strive to have the healthiest pregnancy possible.Second Trimester (Weeks 14 to 27)The second trimester usually has you feeling a bit better physically. While you may have a bit of nausea in the first weeks of the trimester, most of this will dissipate before too long. You may also have a lot more energy now than in the first trimester. Still, there are a few people who simply don't feel great being pregnant. That, however, doesn’t mean that anything is wrong.One thing that many people enjoy about the second trimester is that your baby is getting big enough that your abdomen begins to show a little bump. You may not quite be ready for maternity clothes, but you will notice that your clothes fit differently, and others may notice too. You may also begin to feel the first flutters of your baby’s kicks. You will feel this earlier if you have had a baby before, otherwise by the end of this trimester. While the baby has been moving around a lot since last trimester, it is now getting big enough for you to feel these kicks, punches, and flips.Your baby is growing bigger both in size and in maturity. Your baby is busy doing things like forming fingerprints, and the permanent teeth are forming behind the baby teeth.Third Trimester (Weeks 28+)The end is in sight with this trimester. Article Can I Get Pregnant If I Missed a Pill? Article The Rabbit Test: Origin of the Pregnancy Test A healthy goal is to make it to at least thirty-seven weeks. Your baby is growing larger and stronger. There is brown fat being deposited to help him or her maintain a proper temperature after birth. The lungs are maturing, and the brain is growing and becoming more mature as well. All of these continue to develop all the way through labor.The majority of mothers start feeling tired again. This can also be seen with insomnia, which is not particularly fun as a combination of symptoms. Sometimes you will even see a return to some of the nausea and vomiting you saw in the first trimester. You may also have a few other symptoms including leg cramps, and Braxton Hicks contractions, or "practice contractions."For more information, check out our dedicated section: Your Pregnancy: Week by Week.Emotional Components of PregnancyMany pregnant women and their partners will experience a variety of emotions throughout the pregnancy, which may go overlooked. Sometimes you’re super excited about pregnancy and really happy. But, you can also have periods of being scared or worried about what your life will look like after the baby. Some people will have weird dreams in pregnancy, which can affect mood, or even experience periods of anxiety and/or depression.Brief periods of sadness or anxiety can be normal. However, having periods of negative feelings that last more than a few days is a reason to talk to your doctor or midwife. He or she can offer suggestions that might be helpful.Common Pregnancy ComplicationsWhile most pregnancies are free of complications, the goal of prenatal care is to help prevent and detect complications that can occur. Typically, the earlier a complication is found, the better the outcome will be. An example would be preterm labor. If you are able to detect it early enough, you may be able to stop it or delay it long enough for additional medication to help mature the baby’s lungs.There are other complications that are routinely screened for as well. Some include:MiscarriageEctopic pregnancy (tubal pregnancy)Gestational diabetesPlacenta previaPreeclampsia/eclampsiaGroup B strepFetal malpositionsYou may also have specific concerns based on your medical history. Your practitioner will be helpful at figuring out what you are at the greatest risk for in your pregnancy.Labor and BirthOnce you have reached 37 weeks, labor will not be stopped once it starts. Most women will have their babies two weeks before to two weeks after their due date.Labor is a series of contractions of the uterine muscle that get progressively longer, stronger, and closer together. This force helps the cervix open and the baby to descend through the pelvis and into the birth canal (vagina) until the baby is born.Some mothers choose to labor without medications, instead using natural techniques to relieve pain. This can include many things:Relaxation techniquesMassagePosition changesAromatherapyHydrotherapy (bath or shower)TENS unitsBirth balls/peanut ballsBreathingVisualizationOthers choose medicinal forms of pain relief, from an epidural to IV pain medications. Many women use a combination of natural and medicinal methods to help cope with labor. This can also include the use of professional labor support in the form of a doula.Taking a childbirth class can help you learn about all of your options. It can also help you figure out what options are the best choices for your family. Your class may include information on making a birth plan and even touring your birth facility.To learn more your pain relief options, look to our dedicated section: Methods of Labor Pain Relief.Induction of LaborIf labor does not start on its own by the end of week 42, or if there is a complication that means it is best for the pregnancy to end before labor begins, your practitioner might suggest an induction of labor.Cesarean BirthSometimes, before or during labor, a decision is made that a Cesarean birth (C-section) would be a better option. This is a surgical birth where the baby is born via an incision made in the abdomen and uterus. This may happen for a variety of reasons including, but not limited to:Fetal distressBreech baby or other positionsMaternal complications, such as high blood pressureFetal anomalies (birth defects)Placental complicationsYou should discuss this with your doctor or midwife during pregnancy to figure out what the chances of you needing a C-section are. Sometimes it’s obvious that you are at a higher risk—information that can help you prepare yourself for the possibility.Immediate PostpartumAfter giving birth, you will have a period of recovery. This will include the delivery of the placenta, repair of any tearing on the perineum, and suturing of the uterus and abdomen (as applicable). No matter how you gave birth, you will bleed postpartum. This is from the site of the placenta in the uterus, which is healing.About an hour after delivery, you will typically be moved to your regular postpartum room. If you are in a birth center, you may be released to go home in about three to six hours after giving birth, assuming you and baby are doing well. If you are in the hospital, you will typically stay for a period of two days for a vaginal birth and four days after a Cesarean birth.Your period of recovery technically will end with your six-week visit with your doctor or midwife. This doesn’t mean that you will be back to your pre-pregnancy weight or shape. Remember that it took you nine months to grow a baby and it will take you awhile to feel back to normal. For many women, it is a new normal.Sources:Nerenz RD, Butch AW, Woldemariam GA, Yarbrough ML, Grenache DG, Gronowski AM. Clin Biochem. 2015 Nov 2. pii: S0009-9120(15)00507-X. doi: 10.1016/j.clinbiochem.2015.10.020. [Epub ahead of print] Estimating the hCGβcf in urine during pregnancy.Obstetrics: Normal and Problem Pregnancies. Gabbe, S, Niebyl, J, Simpson, JL. Sixth Edition.Pregnancy Tests. Any Lab Test Now. https://www.anylabtestnow.com/tests/pregnancy-test/ Last Accessed August 28, 2016.Ultrasonography in pregnancy. ACOG Practice Bulletin No. 101. American College of Obstetricians and Gynecologists. Obstet Gynecol 2009;113: 451–61.Your Pregnancy and Childbirth: Month to Month, Revised Sixth Edition. American College of Obstetricians and Gynecologists. 2016.