Pregnancy is the time during which one or more offspring develops (gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins.
Pregnancy usually occurs by sexual intercourse, but can also occur through assisted reproductive technology procedures. A pregnancy may end in a live birth, a miscarriage, an induced abortion, or a stillbirth. Childbirth typically occurs around 40 weeks from the start of the last menstrual period (LMP), a span known as the gestational age. This is just over nine months. Counting by fertilization age, the length is about 38 weeks.[Paverage 8–9 days after fertilization. An embryo is the term for the developing offspring during th first seven weeks following implantation (i.e. ten weeks' gestational age), after which the term fetus is used until birth.
Signs and symptoms of early pregnancy may include missed periods, tender breasts, morning sickness (nausea and vomiting), hunger, implantation bleeding, and frequent urination.Pregnancy may be confirmed with a pregnancy test. Methods of birth control—or, more accurately, contraception—are used to avoid pregnancy.
Pregnancy is divided into three trimesters of approximately three months each. The first trimester includes conception, which is when the sperm fertilizes the egg. The fertilized egg then travels down the Fallopian tube and attaches to the inside of the uterus, where it begins to form the embryo and placenta. During the first trimester, the possibility of miscarriage (natural death of embryo or fetus) is at its highest. Around the middle of the second trimester, movement of the fetus may be felt. At 28 weeks, more than 90% of babies can survive outside of the uterus if provided with high-quality medical care, though babies born at this time will likely experience serious health complications such as heart and respiratory problems and long-term intellectual and developmental disabilities.
Prenatal care improves pregnancy outcomes. Nutrition during pregnancy is important to ensure healthy growth of the fetus. Prenatal care may also include avoiding recreational drugs (including tobacco and alcohol), taking regular exercise, having blood tests, and regular physical examinations. Complications of pregnancy may include disorders of high blood pressure, gestational diabetes, iron-deficiency anemia, and severe nausea and vomiting. In the ideal childbirth, labor begins on its own "at term". Babies born before 37 weeks are "preterm" and at higher risk of health problems such as cerebral palsy. Babies born between weeks 37 and 39 are considered "early term" while those born between weeks 39 and 41 are considered "full term". Babies born between weeks 41 and 42 weeks are considered "late term" while after 42 weeks they are considered "post term". Delivery before 39 weeks by labor induction or caesarean section is not recommended unless required for other medical reasons.
About 213 million pregnancies occurred in 2012, of which, 190 million (89%) were in the developing world and 23 million (11%) were in the developed world. The number of pregnancies in women aged between 15 and 44 is 133 per 1,000 women .About 10% to 15% of recognized pregnancies end in miscarriage. In 2016, complications of pregnancy resulted in 230,600 maternal deaths, down from 377,000 deaths in 1990. Common causes include bleeding, infections, hypertensive diseases of pregnancy, obstructed labor, miscarriage, abortion, or ectopic pregnancy. Globally, 44% of pregnancies are unplanned. Over half (56%) of unplanned pregnancies are aborted. Among unintended pregnancies in the United States, 60% of the women used birth control to some extent during the month pregnancy began.
Birth control, also known as contraception, anticonception, and fertility control, is the use of methods or devices to prevent unintended pregnancy. Birth control has been used since ancient times, but effective and safe methods of birth control only became available in the 20th century. Planning, making available, and using human birth control is called family planning. Some cultures limit or discourage access to birth control because they consider it to be morally, religiously, or politically undesirable.
The World Health Organization and United States Centers for Disease Control and Prevention provide guidance on the safety of birth control methods among women with specific medical conditions. The most effective methods of birth control are sterilization by means of vasectomy in males and tubal ligation in females, intrauterine devices (IUDs), and implantable birth control. This is followed by a number of hormone-based methods including oral pills, patches, vaginal rings, and injections.Less effective methods include physical barriers such as condoms, diaphragms and birth control sponges and fertility awareness methods. The least effective methods are spermicides and withdrawal by the male before ejaculation. Sterilization, while highly effective, is not usually reversible; all other methods are reversible, most immediately upon stopping them. Safe sex practices, such as with the use of male or female condoms, can also help prevent sexually transmitted infections. Other methods of birth control do not protect against sexually transmitted diseases. Emergency birth control can prevent pregnancy if taken within 72 to 120 hours after unprotected sex. Some argue not having sex is also a form of birth control, but abstinence-only sex education may increase teenage pregnancies if offered without birth control education, due to non-compliance.
In teenagers, pregnancies are at greater risk of poor outcomes.Comprehensive sex education and access to birth control decreases the rate of unintended pregnancies in this age group. While all forms of birth control can generally be used by young people, long-acting reversible birth control such as implants, IUDs, or vaginal rings are more successful in reducing rates of teenage pregnancy.After the delivery of a child, a woman who is not exclusively breastfeeding may become pregnant again after as few as four to six weeks. Some methods of birth control can be started immediately following the birth, while others require a delay of up to six months. In women who are breastfeeding, progestin-only methods are preferred over combined oral birth control pills. In women who have reached menopause, it is recommended that birth control be continued for one year after the last menstrual period.
About 222 million women who want to avoid pregnancy in developing countries are not using a modern birth control method. Birth control use in developing countries has decreased the number of deaths during or around the time of pregnancy by 40% (about 270,000 deaths prevented in 2008) and could prevent 70% if the full demand for birth control were met. By lengthening the time between pregnancies, birth control can improve adult women's delivery outcomes and the survival of their children. In the developing world, women's earnings, assets, and weight, as well as their children's schooling and health, all improve with greater access to birth control. Birth control increases economic growth because of fewer dependent children, more women participating in the workforce, and less use of scarce resources.
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