Wednesday, 19 November 2014

PREGNANCY (prevention iz better thn medicines)




The event of fertilization is sometimes used as a mark of the initiation of pregnancy, with the derived age being termedfertilization age, and is an alternative to gestational age. Fertilization usually occurs about two weeks before her nextexpected menstrual period, and if either date is unknown in an individual case it is a frequent practice to add 14 days to the fertilization age to get the gestational age and vice versa.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 is called thegestational age. This choice is a result of a lack of a convenient way to discern the point in time when the actual creation of the baby naturally happens. In case of in vitro fertilisation, gestational age is calculated by days from oocyte retrieval + 14 days.

Development of embryo and fetus

The development of the mass of cells that will become the infant is called 
embryogenesis during the first approximately 10 weeks of gestation. During this time, cells begin to differentiate into the various body systems. The basic outlines of the organ, body, and nervous systems are established. By the end of the embryonic stage, the beginnings of features such as fingers, eyes, mouth, and ears become visible. Also during this time, there is development of structures important to the support of the embryo, including the placenta and umbilical cord. The placentaconnects the developing embryo to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. The umbilical cord is the connecting cord from the embryo or fetus to the placenta.The sperm and the egg cell, which has been released from one of the female's twoovaries, unite in one of the two fallopian tubes. The fertilized egg, known as azygote, then moves toward the uterus, a journey that can take up to a week to complete. Cell division begins approximately 24 to 36 hours after the male and female cells unite. Cell division continues at a rapid rate and the cells then develop into what is known as a blastocyst. The blastocyst arrives at the uterus and attaches to the uterine wall, a process known as implantation.
After about 10 weeks of gestational age, the embryo becomes known as a fetus instead. At the beginning of the fetal stage, the risk of miscarriage decreases sharply, When the fetal stage commences, a fetus is typically about 30 mm (1.2 inches) in length, and the heart can be seen beating via ultrasound; the fetus can be seen making various involuntary motions at this stage. During continued fetal development, the early body systems and structures that were established in the embryonic stage continue to develop. Sex organs begin to appear during the third month of gestation. The fetus continues to grow in both weight and length, although the majority of the physical growth occurs in the last weeks of pregnancy.
Electrical brain activity is first detected between the 5th and 6th week of gestation, though this is still considered primitive neural activity rather than the beginning of conscious thought, something that develops much later in fetation. Synapses begin forming at 17 weeks, and at about week 28 begin to multiply at a rapid pace which continues until 3 to 4 months after birth.[17]

First trimester

Second trimesterMinute ventilation is increased by 40% in the first trimester. The womb will grow to the size of a lemon by eight weeks. Many symptoms and discomforts of pregnancy like nausea and tender breasts appear in the first trimester.
Although the fetus begins to move and takes a recognizable human shape during the first trimester, it is not until the second trimester that movement of the fetus, often referred to as "quickening", can be felt. This typically happens in the fourth month, more specifically in the 20th to 21st week, or by the 19th week if the woman has been pregnant before. It is common for some women not to feel the fetus move until much later. During the second trimester, most women begin to wear maternity clothes.Weeks 13 to 28 of the pregnancy are called the second trimester. Most women feel more energized in this period, and begin to put on weight as the symptoms of morning sickness subside and eventually fade away. The uterus, the muscular organ that holds the developing fetus, can expand up to 20 times its normal size during pregnancy.

Third trimester

Head engagement, where the fetal head descends into cephalic presentation, relieves pressure on the upper abdomen with renewed ease in breathing. It also severely reduces bladder capacity, and increases pressure on the pelvic floor and the rectum.Final weight gain takes place, which is the most weight gain throughout the pregnancy. The woman's abdomen will transform in shape as it drops due to the fetus turning in a downward position ready for birth. During the second trimester, the woman's abdomen would have been very upright, whereas in the third trimester it will drop down quite low, and the woman will be able to lift her abdomen up and down. The fetus begins to move regularly, and is felt by the woman. Fetal movement can become quite strong and be disruptive to the woman. The woman's navel will sometimes become convex, "popping" out, due to her expandingabdomen.
It is also during the third trimester that maternal activity and sleep positions may affect fetal development due to restricted blood flow. For instance, the enlarged uterus may impede blood flow by compressing the lower pressured vena cava, with the left lateral positions appearing to providing better oxygenation to the infant.

Determining gestational age

Since these are spread over a significant period of time, the duration of pregnancy necessarily depends on the date selected as the starting point chosen.
As measured on a reference group of women with a menstrual cycle of exactly 28-days prior to pregnancy, and who had spontaneous onset of labor, the mean pregnancy length has been estimated to be 283.4 days of gestational age as timed from the first day of the last menstrual period as recalled by the mother, and 280.6 days when the gestational age was retrospectively estimated by obstetric ultrasoundmeasurement of the fetal biparietal diameter (BPD) in the second trimester. Other algorithms take into account a variety of other variables, such as whether this is the first or subsequent child (i.e., pregnant woman is a primipara or a multipara, respectively), the mother's race, parental age, length of menstrual cycle, and menstrual regularity), but these are rarely used by healthcare professionals. In order to have a standard reference point, the normal pregnancy duration is generally assumed to be 280 days (or 40 weeks) of gestational age.
The best method of determining gestational age is ultrasound during the first trimester of pregnancy. This is typically accurate within seven days. This means that fewer than 5 percent of births occur on the day of being 40 weeks of gestational age; 50 percent of births are within a week of this duration, and about 80 percent are within 2 weeks. For the estimation of due date, mobile apps essentially always give consistent estimations compared to each other and correct for leap year, while pregnancy wheels made of paper can differ from each other by 7 days and generally do not correct for leap year.
The most common system used among healthcare professionals is Naegele's rule, which was developed in the early 19th century. This calculates the expected due date from the first day of the last normal menstrual period (LMP or LNMP) regardless of factors known to make this inaccurate, such as a shorter or longer menstrual cycle length. Pregnancy most commonly lasts for 40 weeks according to this LNMP-based method, assuming that the woman has a predictable menstrual cycle length of close to 28 days and conceives on the 14th day of that cycle.
As measured from the day of ovulation, the average time to birth has been estimated to be 268 days (38 weeks and two days), with a coefficient of variation of 3.7%.
Accurate dating of pregnancy is important, because it is used in calculating the results of various prenatal tests, (for example, in the triple test). A decision may be made to induce labour if a fetus is perceived to be overdue. Furthermore, if LMP and ultrasound dating predict different respective due dates, with the latter being later, this might signify slowed fetal growth and therefore require closer review.
The stage of pregnancy defined as the beginning of legal fetal viability varies around the world. It sometimes incorporates weight as well as gestational age.It ranges from 16 weeks in Norway, to 20 weeks in the US and Australia, 24 weeks in the UK and 26 weeks in Italy and Spain.


A balanced, nutritious diet is an important aspect of a healthy pregnancy. Eating a healthy diet, balancing carbohydrates, fat, and proteins, and eating a variety of fruits and vegetables, usually ensures good nutrition. Those whose diets are affected by health issues, religious requirements, or ethical beliefs may choose to consult a health professional for specific advice.

Medication use

Drugs used during pregnancy can have temporary or permanent effects on the fetus. Therefore many physicians would prefer not to prescribe for pregnant women, the major concern being over teratogenicity of the drugs.
Drugs have been classified into categories A,B,C,D and X based on the Food and Drug Administration (FDA) rating system to provide therapeutic guidance based on potential benefits and fetal risks. Drugs, including some multivitamins, that have demonstrated no fetal risks after controlled studies in humans are classified as Category A. On the other hand drugs like thalidomide with proven fetal risks that outweigh all benefits are classified as Category