An Overview of Pregnancy

Pregnancy is the period in which an egg cell is fertilized by a sperm to form a new cell, called the zygote, that eventually develops into a new human organism, to be born.

The period of human pregnancy is 40 weeks from the date of the last menstrual period (LMP), or 38 weeks from the time of conception, on average. The former is taken as the beginning of pregnancy in this article.


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Types of pregnancy

Pregnancy can be single or multiple. The latter refers to conceiving two or more fetuses at the same time or conceiving one zygote which divides into two or more separate zygotes at a very early stage of development and forms two fetuses.

If the former, fraternal twins, triplets, quadruplets or quintuplets are formed. If the latter, identical twins (or more multiples) are born as they have the same genetic makeup. While identical twins are fairly common, identical multiples of higher order are very rare.

Trimesters of pregnancy

Pregnancy is divided into three trimesters corresponding to specific stages of fetal growth and development. In the first trimester, covering the first 12 weeks, the fetus is conceived and takes shape from the zygote through the stages of embryonic life.

All the fetal organs are formed during this time. The fetus is called an embryo for the first 12 weeks after the LMP.

In the second trimester, from week 13 to week 28, the organs begin to grow in size and to assume their characteristic shape. The characteristic morning sickness of pregnancy begins to wane towards the beginning or middle of this period.

However, some mothers feel back pain, leg cramps or constipation during this time. The most exciting part of this trimester is quickening when the first tiny fetal movements are felt.

In the third, (week 29 to week 40), the baby begins to grow and develop at a rapid rate. The mother may feel breathless as the uterus with the baby rises to fill a major part of the abdomen, pushing up the diaphragm and reducing the chest cavity. Hemorrhoids, varicose veins and urinary incontinence may occur. Sleeping becomes uncomfortable.

Towards the end of this period, the fetus is full-term and can live outside the mother’s womb independently. The uterus becomes excitable and begins to contract painlessly from the 28th to the 30th week onward. At some point, typically from 37 weeks to 42 weeks, labor sets in and the baby is born.

Complications of pregnancy

Miscarriage is most common during the first trimester of pregnancy. Other first-trimester complications include vaginal bleeding, ectopic pregnancy, and excessive nausea and vomiting.

If the mother decides to have prenatal testing for genetic defects in the baby, finding out about potential or confirmed fetal defects can cause significant stress for the rest of the pregnancy.

In the second trimester, the risk of miscarriage drops dramatically, but preterm labor can still set in. Gestational diabetes mellitus, or high blood sugar levels during pregnancy, typically sets in during this period, as may pregnancy-induced hypertension.

Women may also suffer depression during pregnancy, known as prenatal depression. This is a serious condition that may interfere with everyday life.

In the third trimester, preterm labor, hypertension of pregnancy, abruption or premature separation of the placenta (before the baby is born), are possible complications.

During childbirth, the mother may need operative intervention to deliver the baby for a variety of reasons. Postpartum hemorrhage sometimes complicates the post-childbirth period and is caused by the failure of the uterus to contract, remnants of the placenta left behind in the uterus, an adherent placenta, and several other causes.

Postpartum depression also affects a significant number of women, as does difficulty with breastfeeding

Less commonly, around one in a thousand women develop postpartum psychosis. This is a serious mental illness that is considered a medical emergency.

Medical care during pregnancy

Regular antenatal care can help avoid or manage most pregnancy complications. Typically, doctors suggest monthly checkups until the end of the second trimester, fortnightly visits after that until week 36, and weekly visits beyond that.

Blood tests are typically done to rule out anemia, diabetes, and certain sexually transmitted infections (STIs). An ultrasound scan in the first, second and third trimesters is now usually part of routine antenatal care.

Health during pregnancy

Eating for two is rarely needed as long as the diet is healthy and balanced. Folic acid in the form of a prenatal vitamin is essential to reduce the risk of the baby developing spina bifida, and a supplement containing vitamins and minerals will help ensure the mother gets proper amounts of these during her pregnancy.

While the caloric intake is bound to increase, there is no need to double the intake. Small frequent meals are best to keep the blood sugar and energy level constant while preventing uncomfortable fulness.

Most health services recommend that alcohol is avoided during pregnancy, also excessive (added) salt, sugar, and undercooked animal foods. Unpasteurized dairy foods and milk are considered a potential health risk, as are soft cheeses like Brie or Camembert cheese. It is also recommended that women limit their caffeine intake. The limit is about 200 mg a day, the amount in 12 oz coffee.

Weight gain in pregnancy depends on the stage of pregnancy. Most often, women with normal singleton pregnancies gain 10-12 kg. dieting is not recommended during pregnancy, but women with obesity will probably do well to eat just enough to maintain their weight.

Pelvic floor exercises are beneficial to increase the chances of successful normal delivery and to prevent incontinence and later uterine or bladder descent after childbirth.

Pregnancy often makes many things more difficult to do, such as strenuous exercise. Regular exercise is often recommended to maintain physical fitness in pregnancy but should fit the mother’s physical capabilities.

Pregnant Women Exercising

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Relaxation, plenty of rest, and proper planning about childbirth and life afterward with the new baby will help the mother to pass through this period with hope and excitement and reduce the chances of emotional stress and depression.


[further reading: pregnan

Last Updated: Apr 14, 2020

Dr. Liji Thomas

Written by

Dr. Liji Thomas

Dr. Liji Thomas is an OB-GYN, who graduated from the Government Medical College, University of Calicut, Kerala, in 2001. Liji practiced as a full-time consultant in obstetrics/gynecology in a private hospital for a few years following her graduation. She has counseled hundreds of patients facing issues from pregnancy-related problems and infertility, and has been in charge of over 2,000 deliveries, striving always to achieve a normal delivery rather than operative.


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