Despite the fact few outward changes occur, the earliest months of pregnancy are the most eventful. We take you through the first stages – from the discovery you’re going to have a child.
The quickest way to find out for sure if you are pregnant is to have a pregnancy test. Pharmacists, laboratories with pregnancy testing facilities, hospitals, clinics and GPs may offer the service, or you can buy a do-it-yourself kit to use at home.
All tests work on the same principle, by detecting the presence of the hormone human chorionic gonadotrophin (HGG), which pregnant women excrete in their urine. Only a small sample of urine is needed for the test – and the urine passed first thing in the morning is generally reckoned to be the best for testing purposes, as it is more highly concentrated.
Estimating the delivery date
Pregnancy lasts on average 240 days (approximately nine and a half months) from the first day of the last menstrual period, although conception takes place later in the month. The estimated day of delivery (EDD) is calculated on the day on which the last period started.
Conception takes place around the time of ovulation – which is when the fully ripened egg is released from one of the ovaries. In most women, ovulation happens 14 days before the next menstrual period. So, in an average menstrual cycle of 28 days, conception will take place about two weeks after the last period.
First signs
By the fifth or sixth week of pregnancy there will be definite physical changes. The breasts may feel fuller than normal, and they may even feel rather tender and ‘tingling’. This is because hormonal action is preparing them for breastfeeding.
The blood supply to the breasts is increased throughout pregnancy and milk-producing cells develop. The veins in the breasts become more prominent, and in some women the nipples start to darken in colour.
In these early weeks, small spot-like bumps usually appear on the nipples. They are known as Montgomery’s tubercles, and in a first-time mother their appearance is virtually a confirmation of pregnancy. They are the openings to small glands which secrete a special fluid to keep the skin of the nipples soft and supple.
Hormonal changes
Some women find they need to pass water more often than usual. This is thought to be due to hormonal changes which affect the working of the kidneys. Later, pressure on the bladder from the enlarging uterus will have the same effect. A feeling of tiredness — even exhaustion – often occurs in early pregnancy. This is because the body is doing a lot of unseen work even in these early weeks, and many women and their partners are surprised at how tiring a normal day’s activities can be.
Importance of diet
Eating well is important for the general health of both mother and baby. It has been shown, for example, that certain vitamin or mineral deficiencies such as a shortage of folic acid or insufficient zinc in a mother’s diet may cause defects such as spina bifida or cleft palate in the baby. Adequate quantities of certain other vitamins and minerals may also be necessary to ensure the healthy progress of the pregnancy.
Smoking and drinking
Smoking during pregnancy can cause a baby to be lighter and less physically mature at birth than would otherwise be so. There is also a higher risk that babies of mothers who smoke may be born prematurely or be stillborn.
Too much alcohol during pregnancy may also damage the baby’s health. The effect of an expectant mother’s frequent drinking on her unborn baby can be severe. Alcoholic mothers may give birth to babies with foetal alcohol syndrome, which can include a series of mental and physical defects.
Given the fact that we know alcohol can be harmful, it is best to cut it out altogether, even though most doctors estimate that the possibility of an occasional drink harming the foetus is very small.
The baby
The baby begins as a fertilized egg, or zygote, which is no larger than a tiny speck.
The zygote then develops by the process of cell division, and is swept along the Fallopian tube towards the uterus, where, six days or so later, it begins to embed itself in the wall of the uterus.
The ovaries respond to the pregnancy by producing hormones that stop menstruation. By the time of the missed period, the chorionic villi – finger-like projections of tissue — have entered the womb lining. The chorionic villi transfer nutrients from the mother’s blood to the growing mass of cells.
Embryo to foetus
At this stage, these cells are called the embryo, and, by the start of the second month of the pregnancy, it measures about one centimetre in length. It is rather like a bean in shape – not recognizably human, but with small bump-like outlines which mark where the limbs will form. Throughout the next two months, the shape of the embryo changes, and the arms and legs, hands and feet and even fingers and toes are formed.
The formation of the internal organs has begun by the sixth week after conception. The brain is present in a rudimentary form, and the kidneys, heart, liver and spinal column are there, too. By the sixth week, the amniotic sac – the bag of waters which surrounds the baby in the womb through pregnancy – has also formed.
At the eighth week, the embryo is known as a foetus. Over the following six weeks or so, all the major structures of the unborn baby’s body will have developed. The rest of the pregnancy is used, in the main, as growing time, to build on what is already there.
By the end of three months eyes, eyelids, finger and toenails and the external sex organs have all been formed. But the body is fairly soft, although there is a sort of skeletal structure giving a supporting framework to it.
At this stage, the foetus is about 10cm long, and it lies in a curled-up position.
Role of the placenta
At the end of week 14 the placenta is fully functioning. It is formed from the chorionic villi, and is firmly attached to the wall of the uterus. It is also joined to the foetus by the umbilical cord.
The placenta not only produces hormones which sustain the pregnancy, but also passes on the nourishment that the foetus needs in order to grow. Nutrients from the mother’s blood reach the placenta, which then channels them into the bloodstream of the foetus via the
vein in the umbilical cord. Waste products from the foetus are in turn passedto the placenta through the umbilical arteries. The placenta also prevents certain toxic substances from reaching the foetus, although it cannot always screen the foetus from harm.