Pregnancy Overview
Pregnancy occurs when a sperm fertilizes an egg after it’s released from the ovary during ovulation. The fertilized egg then travels down into the uterus, where implantation occurs. A successful implantation results in pregnancy.
On average, a full-term pregnancy lasts 40 weeks. There are many factors that can affect a pregnancy. Women who receive an early pregnancy diagnosis and parental care are more likely to experience a healthy pregnancy and give birth to a healthy baby.
Knowing what to expect during the full pregnancy term is important for monitoring both your health and the health of the baby. If you’d like to prevent pregnancy, there are also effective forms of birth control you should keep in mind.
Pregnancy, or gestation, is a period of around 9 months when an unborn baby is developing in the uterus. The first sign of pregnancy is usually missed menstruation, but there are also others.
Most pregnancies last for about 280 days, which is somewhere around 40 weeks. A pregnancy calculator can help predict when a baby is likely to be born.
Early Signs and Symptoms of Pregnancy
Every woman is different. So are their experiences of pregnancy. Not every woman has the same symptoms or even the same symptoms from one pregnancy to the next.
Also, because the early symptoms of pregnancy often mimic the symptoms you might experience right before and during menstruation, you may not realize you’re pregnant.
These early signs and symptoms may be caused by other factors besides being pregnant. Therefore, the fact that the individual may notice some of these symptoms does not necessarily mean you are pregnant. The only way to tell for sure is with a pregnancy test.
Following are some of the common signs and symptoms before you even take a pregnancy test. Others will appear weeks later, as the hormone levels change:
- Back pain
- Breast changes such as tenderness
- Constipation
- Dizziness
- Fatigue
- Fainting
- Frequent urination due to hormonal changes and increased blood flow through the kidneys
- Headaches
- Light implantation bleeding or spotting
- Mood swings
- Nausea with or without vomiting
- Tiredness
Not every pregnant woman experiences the same symptoms and some experience no symptoms at all. A pregnant woman could have all of these symptoms, or maybe have only one or two
Breast Changes
Breast changes are another very early sign of pregnancy. A woman’s hormone levels rapidly change after conception. Because of the changes, their breasts may become swollen, sore, or tingly a week or two later. Or they may feel heavier or fuller or feel tender to the touch. The area around the nipples, called the areola, may also darken.
Other things could cause breast changes. But if the changes are an early symptom of pregnancy, keep in mind that it is going to take several weeks to get used to the new levels of hormones. But when it does, breast pain should ease up.
Fatigue
Feeling very tired is normal in pregnancy, starting early on. A woman can start feeling unusually fatigued as soon as one week after conceiving.
This is often related to a high level of a hormones called progesterone, although other things, such as lower levels of blood sugar, lower blood pressure, and a boost in blood production can all contribute.
If fatigue is related to pregnancy, it’s important to get plenty of rest. Eating foods that are rich in protein and iron can help offset it.
Missed Period
One of the most common early signs of pregnancy is a missed menstrual cycle. According to the American Pregnancy Association, 29% of pregnant women have reported this as their first sign of being pregnant.
The most obvious early symptom of pregnancy and the one that prompts most women to get a pregnancy test, is a missed period. But not all missed or delayed periods are caused by pregnancy.
Also, women can experience some bleeding during pregnancy. If you are pregnant, ask your doctor what you should be aware of with bleeding. For example, when is bleeding normal and when is it a sign of an emergency?
There are reasons, besides pregnancy, for missing a period. it might be that you gained or lost too much weight. Hormonal problems, fatigue, or stress are other possibilities. Some women miss their period when they stop taking birth control pills. But if a period is late and pregnancy is a possibility, you may want to get a pregnancy test.
Nausea
Morning sickness or nausea is a famous symptom of pregnancy. But not every pregnant woman gets it.
The exact cause of morning sickness is unknown, but pregnancy hormones likely contribute to this symptom. Nausea during pregnancy may occur at any time of the day but most commonly in the morning.
Also, some women crave, or can’t stand, certain foods when they become pregnant. That’s also related to hormonal changes. The effect can be so strong that even the thought of what used to be a favorite food can turn a pregnant woman’s stomach.
Spotting and Cramping
After conception, the fertilized egg attaches itself to wall of the uterus. This can cause one of the earliest signs of pregnancy, spotting and, sometimes, cramping.
Confirmation of a Pregnancy
To confirm a pregnancy, a person can:
- Perform a home pregnancy test
- Consult with their doctor for a physical exam and a blood pregnancy test
A pregnancy test detects the human chorionic gonadotropin (HCG) hormone in the blood or urine. HCG is present just a few days after becoming pregnant.
Levels of the hormone are low at the beginning of pregnancy, and they gradually increase. Having a high level of HCG can signal a multiple pregnancy, such as when a person is pregnant with twins or triplets.
If a pregnancy test is positive, a person can get an abdominal or transvaginal ultrasound scan.
The scan can confirm the following:
- How many embryos there are
- The gestational age of the pregnancy
- Whether the placement is correct in the womb
Stages of Pregnancy
Doctors measure the fetal age of the baby from the date of conception. But they may determine a pregnant person’s due date by looking at the gestational age, which they measure by counting the pregnancy from the first day of the person’s last menstruation. This includes the period of ovulation and conception.
The following guide follows the gestational age measurement of pregnancy.
Weeks 1-13
The first trimester runs through the first 13 weeks, including the period of ovulation and conception.
Conception and Implantation
Conception occurs when sperm from a male penetrates an egg from a female and fertilizes it. This usually happens in the female’s fallopian tube after ovulation. The result is a zygote, a unified sperm and egg cell.
Afterward, the zygote immediately starts to divide, forming a cluster of cells called an embryo.
After dividing and growing, the embryo attaches to the wall of the uterus and puts out root-like veins called villi. This process is called implantation.
Occasionally, the embryo implants somewhere other than the lining of the uterus, usually in the fallopian tube. This results in an ectopic pregnancy.
When the embryo implants normally, the villi ensure that the embryo is anchored to the lining of the uterus. They will eventually become the placenta, which feeds and protects the embryo as it develops, supplying it with oxygen and nutrition, and expelling waste.
Early Development
The embryo then begins to develop quickly. The first things to develop are the heart, spinal cord, brain, and gastrointestinal tract. The placenta begins to form. As time goes on, more structures and organs grow.
By week 6, a doctor may be able to detect a heartbeat. By week 7, most essential organs are already forming. By week 8, everything that adult humans have both inside and out is present in the embryo in a much smaller form.
By week 9, the embryo becomes a fetus and continues to develop inside the uterus, surrounded by amniotic fluid. This is the “water” that “breaks” just before delivery. By the end of this stage, the fetus will grow to about 3 inches (in) in length and a weight of about 1 ounce (oz).
Expected Symptoms
In the first 13 weeks, the symptoms of pregnancy will likely be similar to those that may occur at the earliest stages, but they may increase as time goes on.
Additional symptoms a pregnant person may encounter at this time include mood swings, changes in appetite or cravings for certain foods, constipation, headaches, and heartburn.
While some pregnant people may gain weight at this stage, others may lose weight. Not all people experience these symptoms, as every pregnancy is different.
Weeks 13-28
In the second trimester, the fetus forms a type of fine hair called lanugo on its head. It also begins to suck and forms fingerprints.
The sweat glands, eyebrows, eyelashes, and eyes begin to form. The brain, the nervous system, and other essential organs continue to develop.
By week 22, if a fetus is born, it may be able to survive with medical intervention. By week 28, the fetus will grow to about 2 ¼ pounds (lbs) in weight and a length of 14 inches.
Expected Symptoms
In the second trimester, pregnant women will usually begin to gain weight. They may begin to feel the movements of the fetus, and others can often feel them by placing a hand on the pregnant person’s abdomen.
Many pregnant women feel more comfortable in the second trimester. Nausea usually stops, and energy levels are often higher. Some women may still experience some discomfort. This may include back pain, carpal tunnel syndrome, itching on the palms of hands or soles of feet, and swelling of the face, fingers, or ankles.
If the swelling is sudden or severe, or if the itching goes along with vomiting, nausea, jaundice, fatigue, or loss of appetite, a patient should check with a doctor. These may be signs of preeclampsia or a problem with the liver.
Some women may also notice some discoloration of the skin and may begin to see stretch marks on their body.
Weeks 29-40
The third trimester lasts from week 29 until birth, which is commonly week 40. In the first few weeks of this period, the fetus will really grow in size. It will begin to make some rhythmic breathing movements with its lungs, although these are still developing.
The bones develop fully by this time, but they are still soft. The eyelids will open. After week 33, the fetus will usually make its way into a head-down position in preparation for birth. It will continue to gain more weight and lose its lanugo hair.
From 38 weeks the fetus is considered full-term. It may weigh anywhere from 6 ¾ to 10 lbs with a length of about 16-19 inches.
Expected Symptoms
Many of the same symptoms from previous weeks may continue during this time. A pregnant woman may experience increased back pain and find it more difficult to rest comfortably. They may urinate more often, due to the pressure on the bladder. In addition, indigestion can result when the fetus pushes against the stomach.
Additional symptoms may include things like hemorrhoids, shortness of breath as the baby presses on the diaphragm, and insomnia.
Some women may find that their breasts are leaking colostrum, a pre-milk substance that the body produces in preparation for milk production.
Early contractions may also occur days or weeks before birth. Doctors call these Braxton-Hicks contractions. These do not indicate labor.
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