A missed period in a woman of childbearing age who has been previously regular is often the earliest symptom of pregnancy. This is not always a sure sign because there are other conditions which bring about a sudden cessation of menstrual periods. But if a second period is missed, pregnancy must be regarded as the most likely explanation.

It is essential to consult the specialist once you feel that you are pregnant, so as to have a regular check up, get advice on nutrition, correction of anemia and treatment of pre-existing diseases like diabetes or chronic infections and also for problems connected with pregnancy.

Do not forget to ask your specialist regarding the drugs you can take and drugs which you should not, as some of these drugs may harm the fetus. Antenatal care is of primary importance even if everything is normal, and should start as soon as pregnancy is detected.

Breasts get enlarged and tender, often generating a feeling of discomfort and tenseness. The areola (dark area around the nipple) and the nipple itself assume a darker colour and blood vessels become visible.

Early in pregnancy many women find an increased desire to pass urine as a result of the pressure of the enlarged uterus (womb) on the urinary bladder. The symptom disappears in about three months when the uterus expands upward into the abdomen.

An expectant mother feels her baby move within her ('quickening') after the fourth month. The movements increase and become stronger and more vigorous as the baby grows.

Conception explained

In women, the organs of reproduction consist of the ovaries, the fallopian tube, the uterus (womb), and the vagina (see illustration).

From puberty (when periods begin) to menopause (complete stoppage of menstrual periods) a female cell (ovum) ripens in the ovary once a month. The ripe ovum is shed from the ovary, usually between the twelfth and fourteenth days of the menstrual cycle (counted from the first day of the last period). Muscle contractions propel the ovum towards the uterus through the fallopian tube.

Millions of male cells (sperm) pass into the vagina during sexual intercourse. They can move by themselves, unlike the female cells. Some of them propel themselves into the uterus and thence to the fallopian tube, usually within an hour after intercourse.

When one of these sperm unites with the ovum, conception takes place.

Neither the male cell nor the female cell is capable of growing by itself. But when they are united a complete cell capable of growth is formed. It soon divides into two cells, and the two divides into four and so on when a cluster of cells is formed it is called an embryo. Within three to five days after conception the embryo moves down the fallopian tube into the uterus and sinks into its soft lining (see illustrations). Up to this time the embryo has been getting its food from the original female cell which is now exhausted.

How the baby grows

Second week: Little finger-like structures fasten the embryo to the lining of the womb. Three different groups of cells have been forming : one group will develop into the body; the second will form the attachment to the uterus - the placenta - which will be joined to the baby by the umbilical cord; the third will develop into the membranes surrounding and protecting the baby.

Third week: The embryo is now a grooved oblong. Many beginnings of organs are present.

Fourth week: The embryo is now 4.24 mm. (one-sixth of an inch) long. Internal organs begin to form. Heartbeats start, though inaudible yet.

Fifth week: The backbone begins to form. The head is developing. Tiny limb buds appear.

Sixth week: The embryo is 12.7mm. (half an inch) long. Arms and legs with tiny webbed fingers and toes appear. Internal organs are growing fast.

Seventh week: the ears and eyelids are forming.

Third month: The placenta and the membranes have formed. The membranes form a sac which contains a fluid in which the baby floats. The fingers and toes lose their webs. The baby is about 6.36 cm. (2.1/2 inches) long now and weighs 14.15 grams (1/2 oz.)

Fourth month: Nails begin to appear. A little hair starts growing. The teeth are forming. The baby now weighs about 113.4 gm. (4 oz.) and is 12.7 cm (5 inches) long. Muscles begins to be active.

Fifth month: The doctor can now hear the heart-beats of the baby through a stethoscope. The baby begins slight movements which are felt by the mother. At 20 weeks the baby weighs 298 gm. (10.1/2 oz.). The mother's abdomen is now large enough for her condition to be noticed.

Sixth to ninth month: The baby's movements become real thumps by the sixth month. His body grows fast. He has red, wrinkled skin. Body fat is formed. His skin has a soft, downy fuzz.

Full term: The fuzz disappears. His skin has a natural colour now. The average weight is 3.18kg (7 lb.) and the average length 50.7 cm (20 inches). He has fine hair on his head. He is now fully grown, but his lungs and digestive organs will start functioning only after birth.

How the baby gets his food and oxygen

During pregnancy the placenta grows with the baby. Blood vessels from the baby's body run through the umbilical cord into the placenta where they pass close to the mother's blood vessels. There is no direct connection between the blood streams of mother and child. Food substances from the mother's body pass on to the baby through the blood vessel walls in the placenta. Waste products from the baby are passed back in the same way. The baby does not breath while he is in his mother's womb. He gets his oxygen from the mother's blood.

The fluid in which he floats has an even temperature and acts as a shock-absorber to protect him from the jolts and bumps he may otherwise receive from the normal activity of his mother.

The baby's sex

Scientific studies so far undertaken suggest that the male cell determines where the baby will be a boy or a girl. One kind of male cell will cause a baby boy and the other a baby girl. Which of the two fertilises the female cell is a matter of chance.

Suitable tests have been devised to discover before birth whether the baby is a boy or a girl. Examination of fluid taken from the mother's womb between 16th and 18th week of pregnancy helps in determining the sex of the fetus.

Twins

By listening to the heart-beats through a stethoscope a doctor can tell whether a woman is going to have twins. He can also discover the fact in advance by examining her abdomen. An X-ray after the fourth month will definitely establish whether twins are present.

Twins are of two kinds - "fraternal" and "identical". Fraternal twins come from two female cells that have been fertilised by two male cells. They are separate babies from the start; each has its own placenta and bag of waters. Fraternal twins are not always alike and need not necessarily belong to the same sex.

Identical twins are caused by the embryo formed after the union of one male cell and one female cell, which has separated into two parts for some unknown reasons. They have separate umbilical cords and bags of waters but are attached to the same placenta. They are always of the same sex and look very much alike.

Triplets and quadruplets can belong to either variety - fraternal or identical. But they are born very seldom. Twins are born about one in 86 pregnancies on an average - about 25 per cent of them are identical twins.

When is the baby due?

It is not possible to predict the exact date on which the baby will arrive. For an approximate date, count back three months from the first day of the last menstrual period (before pregnancy) and add seven days. For example, if your last period began on December 1, count back to September 1 and add seven days. The baby will be due about September 8. Most babies arrive within a week of the expected time.

Keep everything ready for the baby's arrival at least 4 to 8 weeks beforehand as some babies are born before they are due.