Page 118 - 86 human physiology part-2

Pregnancy and Birth

This is more common with genetic defects, such as Factor V Leiden. This complication will
prevent blood flow to and from the baby and many times will cause the placenta to also clot and die. If
this is not caught early enough, the baby will die of starvation in the womb. A simple ultrasound can
determine if there are problems with the blood flow.

Pregnancy from the mother's perspective

The first sign you may be pregnant is missing your period. This is because the blastocyte that is in
your uterus has special cells that release the hormone hCG (beta-human chorion gonadotrophin). HCG
is the hormone used in a home pregnancy test to determine if a woman is pregnant. If it is positive, the
woman should follow up with a visit to the doctor in which a blood sample will be taken for
confirmation.

Pregnancy is the carrying of one or more embryos, or fetuses, by female mammals including
humans, inside their bodies. In a pregnancy, there can be multiple gestations (for example, in the case
of twins, or triplets). Human pregnancy is the most studied of all mammalian pregnancies.

Human pregnancy lasts approximately 9 months between the time of the last menstrual cycle and
childbirth (38 weeks from fertilization). The medical term for a pregnant woman is genetalian, just as
the medical term for the potential baby is embryo (early weeks) and then fetus (until birth). A woman
who is pregnant for the first time is known as a primigravida or gravida 1: a woman who has never
been pregnant is known as a gravida 0; similarly, the terms para 0, para 1 and so on are used for the
number of times a woman has given birth.

In many societies' medical and legal definitions, human pregnancy is somewhat arbitrarily divided
into three trimester periods, as a means to simplify reference to the different stages of fetal
development. The first trimester period carries the highest risk of miscarriage (spontaneous death of
embryo or fetus). During the second trimester the development of the fetus can start to be monitored
and diagnosed. The third trimester marks the beginning of viability, which means the fetus might
survive if an early birth occurs.

Changing Body

As soon as a woman becomes pregnant, her body begins to change so that it can support both
herself and the unborn baby. All of the body functions start to work much harder. The heart has to
pump more blood around the body, in particular to the womb, placenta, and the fetus. As well as
physical demands, pregnancy also causes a range of emotional reactions.

• The first trimester, the first twelve weeks, little is visible.
• The second trimester, 13-27 Weeks, the waistline is rapidly growing, the abdomen becomes
noticeably pregnant.
• The third trimester, 28-40 weeks, the body expands rapidly and the womb enlarges and
presses against the diaphragm.

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