pregnancy

Topics: Pregnancy, Embryo, Fetus Pages: 5 (1205 words) Published: January 20, 2014
Pregnancy is the fertilization and development of one or more offspring, known as an embryo or fetus, in a woman's uterus. It is the common name for gestation in humans. A multiple pregnancy involves more than one embryo or fetus in a single pregnancy, such as with twins. Childbirth usually occurs about 38 weeks after conception; in women who have a menstrual cycle length of four weeks, this is approximately 40 weeks from the start of the last normal menstrual period (LNMP). Human pregnancy is the most studied of all mammalian pregnancies. Conception can be achieved through sexual intercourse or assisted reproductive technology.

An embryo is the developing offspring during the first 8 weeks following conception, and subsequently the term fetus is used until birth.[1][2] In many societies' medical or legal definitions, human pregnancy is somewhat arbitrarily divided into three trimester periods, as a means to simplify reference to the different stages of prenatal development. The first trimester carries the highest risk of miscarriage (natural death of embryo or fetus). During the second trimester, the development of the fetus can be more easily monitored and diagnosed. The beginning of the third trimester often approximates the point of viability, or the ability of the fetus to survive, with or without medical help, outside of the uterus.[3]

In the United States and United Kingdom, 40% of pregnancies are unplanned, and between a quarter and half of those unplanned pregnancies were unwanted pregnancies.[4][5] Of those unintended pregnancies that occurred in the US, 60% of the women used birth control to some extent during the month pregnancy occurred.[6] Contents

1 Terminology
2 Physiology
2.1 Initiation
2.2 Development of embryo and fetus
2.3 Maternal changes
2.4 Duration
2.5 Childbirth
2.6 Postnatal period
3 Diagnosis
3.1 Physical signs
3.2 Biomarkers
3.3 Ultrasound
4 Management
4.1 Attending prenatal care
4.2 Nutrition
4.3 Weight gain
4.4 Medication use
4.5 Use of recreational drugs
4.6 Exposure to environmental toxins
4.7 Sexual activity
4.8 Exercise
5 Symptoms and discomforts
6 Complications
7 Intercurrent diseases
8 Epidemiology
9 Society and culture
9.1 Arts
9.2 Infertility
9.3 Abortion
9.4 Legal protection
10 References
11 Additional images
12 Further reading
13 External links

Terminology

One scientific term for the state of pregnancy is gravidity (adjective "gravid"), Latin for "heavy" and a pregnant female is sometimes referred to as a gravida.[7] Similarly, the term parity (abbreviated as "para") is used for the number of times a female has given birth, counting twins and other multiple births as one pregnancy, and usually including stillbirths. Medically, a woman who has never been pregnant is referred to as a nulligravida, a woman who is (or has been only) pregnant for the first time as a primigravida,[8] and a woman in subsequent pregnancies as a multigravida or multiparous.[7][9] Hence, during a second pregnancy a woman would be described as gravida 2, para 1 and upon live delivery as gravida 2, para 2. An in-progress pregnancy, as well as abortions, miscarriages, or stillbirths account for parity values being less than the gravida number. In the case of twins, triplets etc., gravida number and parity value are increased by one only. Women who have never carried a pregnancy achieving more than 20 weeks of gestation age are referred to as nulliparous.[10] Physiology

Timeline of pregnancy by gestational age.
Initiation
See also: Human fertilization
Fertilization and implantation in humans.

The most commonly used event to mark the initiation of pregnancy is the first day of the woman's last normal menstrual period, and the resulting fetal age...
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