If a woman has the other signs but does not miss a period, she is not pregnant.
If you think you think you might be pregnant, a home pregnancy can help you find out for sure.
Pregnancy lasts for about 280 days, or 40 weeks. A pregnancy calculator can help to predict when a baby is likely to be born.
The three stages of pregnancy are known as trimesters. Each one lasts approximately 3 months.
Apart from missing a period, early signs of pregnancy are:
- Nausea with or without vomiting
- Breast changes
- Breast tenderness
- Frequent urination
Nausea generally occurs during the first 3 to 4 months of pregnancy, while tiredness tends to be more prevalent during the first and last three months, or trimester.
To confirm a pregnancy, a woman can:
- See a doctor
- Buy a home pregnancy test
If the home pregnancy test indicates that a woman is pregnant, she should see a health care professional for further confirmation.
A doctor can then make sure she receives proper advice and support from the beginning of the pregnancy.
A pregnancy test works by detecting the hormone human chorionic gonadotropin (HCG) in the woman's blood or urine. HCG is present in a woman as soon as she becomes pregnant, even before her period is due. The more HCG there is, the higher the chances of having a multiple pregnancy.
However, this needs to be confirmed with an abdominal, or transvaginal scan. The scan can tell how many embryos there are, as well as checking that the embryo is in the correct place in the womb.
What happens during pregnancy?
Conception occurs when a male sperm penetrates a female egg and fertilizes it. This usually happens in the woman's fallopian tube, after ovulation. This creates a zygote.
As soon as the egg is fertilized, the zygote starts to divide, and it keeps dividing until there is a cluster of cells. This is known as an embryo.
After 5 to 7 days of dividing and growing, the cluster of cells attaches itself to the wall of the uterus, or womb, and puts out root-like veins called villi.
The villi ensure the embryo is anchored to the lining of the uterus. They will eventually become the placenta, which feeds and protects the embryo or fetus as it develops, supplying it with oxygen and nutrition, and expelling waste.
During the next 12 weeks, the bones, muscles, blood, nervous system, and most of the internal organs start to form. When this is complete, the embryo is known as a fetus. A fetus is about 1 inch long, the ears and facial features are evident, and the fingers and toes are starting to appear.
The fetus develops inside the uterus, surrounded by amniotic fluid. This is the "water" that "breaks" just before the infant is born.
Most pregnancies last from 37 to about 42 weeks. The due date is calculated from the first day of the last period.
Pregnancy, trimester by trimester
The 1st trimester is the first 13 weeks. The embryo develops quickly at this stage. Tiredness, nausea, and breast tenderness are common.
The 2nd trimester lasts from week 14 to 26. The mother will gain weight and develop extra reserves of fat. She will feel the movement of the fetus, and others will feel them too if they place their hands on the mother's abdomen. Movement may be visible.
The 3rd trimester last from week 27 until birth. The baby will build up stores of fat and the lungs and sense of hearing, taste, and sight will develop.
The mother may experience back pain and find it harder to get comfortable for a good night's sleep. She will also urinate more often due to the pressure on her bladder.
Early contractions may occur days or weeks before birth, known as Braxton Hicks contractions. These are not the contractions of labor.
It is important to keep in touch with the health services during pregnancy.
The first visit
The first antenatal appointment is usually within the first 12 weeks.
An ultrasound checks that everything is going to plan.
A doctor will take note of the mother's general health and any issues that may need additional treatment or care and will advise her about how to eat and live healthily during pregnancy.
Health care providers will inform the mother about pregnancy care services in her area and any financial assistance she requires.
There will normally be an ultrasound scan. This uses sound waves to produces an image of the baby inside the mother, and it gives a closer prediction of the birth date. It can also show if there is just one fetus, twins, or more.
A second scan may take place between 18 and 20 weeks, to confirm whether the baby is developing normally.
Some optional tests may help detect possible conditions that may affect the health of the mother or the fetus.
These include tests for:
- Anemia, or red blood cell deficiency: A woman may need nearly 50 percent extra iron during pregnancy, to produce hemoglobin. Hemoglobin in red blood cells carries oxygen to other cells.
- Down syndrome: The risk increases with age. For a woman in her 20s, the risk is 1 in 1,500, in her 30s 1 in 800, at 35 it is 1 in 270, at 40 it is 1 in 100, and at 45 it is 1 in 50. Screening can detect whether the baby has Down syndrome.
- Fetal abnormalities: Blood tests can detect various syndromes and abnormalities from week 9.
- Hepatitis B: In the United States, approximately 1 in every 500 to 1,000 pregnant women has hepatitis when she gives birth, and this can affect the infant.
- Rubella, or German measles: The risk is very small, but it can lead to miscarriage or multiple birth defects and developmental problems.
Gestational diabetes can develop during pregnancy. It has few symptoms and usually resolves after giving birth.
The HIV virus can be passed on to the fetus during pregnancy, labor, delivery, and through breastfeeding, but medications can prevent HIV transmission to the fetus.
In time, the mother may be invited to antenatal classes that will provide information about giving birth and about taking care of the newborn and herself.
Common causes of discomfort during pregnancy include:
A gynecologist will check your health and give important advice.
- Genital infections
- High or low blood pressure
- Gum disease
- Nausea and vomiting
- Urinary tract infections
Some complications of pregnancy will need medical intervention.
Miscarriage refers to the loss of a pregnancy. It usually happens during the first trimester. The first sign is normally vaginal bleeding and possibly abdominal pain, or back pain.
Ectopic pregnancy is when the zygote does not implant in the lining of the uterus, but elsewhere. It can lead to significant internal bleeding and is potentially fatal for the mother.
Symptoms may include pain at the tip of the shoulder, vaginal bleeding, pain on one side of the abdomen, pain when urinating or passing stools.
Pre-eclampsia refers to hypertension, or high blood pressure, either during pregnancy or just after delivery. Apart from hypertension, there will be protein in the urine and edema that may cause swelling in the face, hands, feet and ankles. There may be rapid weight gain, vision problems, abdominal pain, and headaches.
Placenta previa is when the placenta covers part or all of the cervix, the exit from the uterus through which the baby passes. This normally resolves itself, but, if not, a cesarean section may be necessary.
Obstetric cholestasis is when bile builds up in the blood, possibly leading to preterm birth.
A molar pregnancy happens when the sperm fertilizes the egg, and the pregnancy appears to progress normally, but a genetic problem prevents the embryo from developing. This normally results in miscarriage.
Stillbirth is when an infant is born after 24 weeks of pregnancy without signs of life.
To reduce risks of complications, it is important to:
- Keep physically active to maintain general health and body weight and help with labor and delivery. Walking or swimming are suitable activities, but contact sports are not advised.
- Avoid excessive weight gain, apart from what is necessary for the pregnancy. A woman with obesity should not gain weight during pregnancy.
- Avoid tobacco smoke by not smoking or by asking others to smoke outside. Exposure to tobacco increases the risk of disease for the child in later life. Exposure to air pollution should also be avoided as much as possible.
- Avoid alcohol, as it can cause fetal alcohol syndrome.
- Avoid marijuana or cannabis, as they might have harmful effects on the unborn baby.
- Use only medications or natural remedies that are agreed with a physician.
- Avoid fish that may have high levels of mercury, especially shark, marlin, swordfish, and barracuda.
- Follow a healthy and balanced diet, with plenty of fruits, vegetables, whole grains, and at least 2 liters of water or fluid a day.
- Reduce or cut out caffeine, as it may affect fetal growth.
Some bacterial infections from food, especially salmonella or listeriosis, can harm the fetus. These can come from cured, uncooked, or undercooked foods, and cheeses that are ripened with mold, such as Camembert.
Soil and some animal feces can transmit infections. Toxoplasmosis, from cat feces, can cause severe harm to the unborn fetus. It is important to wear gloves and wash hands before and after gardening or changing cat litter.
An infant who is born too early is "preterm." The earlier the birth, the higher the chance of complications, as the infant's body systems will not be developed enough to survive outside the womb.
Some women choose to deliver in a birthing pool.
An infant born at or after 39 weeks is likely to be fully developed. If a pregnancy lasts 42 weeks, the birth will probably be induced.
If there are no complications during pregnancy, some women may have the option of giving birth at home, but it is important to remember that if a problem arises during the birth, it will take longer to access medical help.
When the time comes to deliver, a woman has some choice regarding the type of pain relief she will use, and some hospitals offer the use of a birthing pool, where delivery takes place in water.
These are all safe options as long as they are carried out under the supervision of medical professionals.
It is important to discuss all options with a healthcare provider and to follow the instructions and advice they give.