Pregnancy-related changes take place not only in the reproductive organs but also elsewhere in the maternal body. There is often an increased sleep requirement and as the pregnancy progresses the woman becomes more easily fatigued. The general well-being can be positively influenced by a fulfilled pregnancy wish and negatively by pregnancy-related discomforts or complaints. Some changes are noticed by the pregnant woman herself (e.g. tender breasts) and others are not; however these can be objectively determined (e.g. the decrease in total lung capacity).
The physiological changes described above do not occur in every pregnant woman to the same extent. Some of these changes, the complaints that can arise as a consequence of these and the therapeutic options will be briefly discussed.
Blood volume and composition
During pregnancy the circulating blood volume increases by about 40%. There is an increase in the total number of erythrocytes (15-20%) due to the increased demand for oxygen. The most important, however, is the increase in plasma volume. This is the consequence of generalised vasodilation during pregnancy, which is probably due to an increased production of prostacyclin, greater blood flow through the heart and kidneys, and the extensive uterine vascular bed.
The increase in plasma volume is proportionately greater than the rise in the total number of erythrocytes, giving rise to haemodilution. This results in a decrease in various blood components such as the haemoglobin level, the haematocrit and the number of thrombocytes per millilitre. This is often referred to as the physiological anaemia of pregnancy, which indicates that the normal Hb levels during pregnancy are lower than those outside of pregnancy. However, during pregnancy there is a considerable risk of genuine anaemia. Therefore it is important to monitor haemoglobin levels (see also ‘Physical diagnostics and laboratory tests’ and ‘Regular check-ups during pregnancy’).
The peripheral resistance decreases due to an increase in the uteroplacental circulation and general vasodilation, which some pregnant women perceive as a feeling of warmth.
Heart and circulation
The heart rate increases (by 10 to 15 beats per minute), as does the stroke volume. As a result of this the heart minute volume increases by about 40% (1.5 litres per minute) to provide the growing uterus with oxygen and nutrients. Systolic blood pressure remains virtually unchanged. Diastolic blood pressure initially falls by about 10-15 mmHg until the 20th week and returns to the original level towards the end of the pregnancy. The woman can experience the increased pulse pressure and heart rate as unpleasant. Harmless arrhythmias frequently occur during pregnancy. Venous return from the lower extremities is hindered by the growing uterus, causing an increase in venous pressure and static oedema. As a result of this, varicose veins in the vulva, anus (haemorrhoids) and legs can develop or worsen. Whether, and to what extent, varicose veins occur is mainly determined genetically. The increased volume of circulating and (partly due to the decreased colloid osmotic pressure) extracellular fluid can cause swelling of the legs in the presence of orthostatic congestion.
During the night this fluid is once again mobilised, which results in increased diuresis (nocturesis).
In the supine position the vena cava can be almost completely occluded due to the weight of the pregnant uterus. If insufficient collateral circulation exists, supine hypotensive syndrome develops. Due to obstruction of venous return, the heart minute volume and blood pressure decrease and the woman is at risk of collapse. The foetus also becomes distressed due to the decreased placental circulation. Once the woman turns to the semi-prone position, recovery occurs quickly.
Lungs
The total lung capacity decreases during pregnancy due to the increased angle of the lowest costal arch, as a result of which the transverse diameter of the thorax increases and the diaphragm assumes a higher position. However the breathing volume still increases. The woman breathes slightly more deeply because the sensitivity of the respiratory centre for CO2 increases under the influence of progesterone. A certain degree of hyperventilation develops due to the greater demand for oxygen. The woman sometimes experiences this as dyspnoea.
Urinary tract
Early in pregnancy, renal circulation increases considerably and, with this, glomerular filtration. The renal threshold for glucose is lowered as a result of which glucosuria sometimes occurs.
Frequent urination often occurs. The most important cause of this appears to be mechanical pressure from the pregnant uterus and, towards the end of pregnancy, the presenting part of the foetus on the bladder.
Muscle weakening under the influence of progesterone might play a role as well. Once cystitis has been excluded, frequent urination does not require treatment.
At the end of pregnancy the bladder is pushed upwards due to the dropping of the foremost part of the foetus, as a result of which urinary retention and incontinence can occur. Compression of the ureters between the pregnant uterus and the bony pelvis can lead to congestion in the renal pelvis. This usually concerns the right kidney. Retention of urine in the renal pelvis or bladder increases the chance of a urinary tract infection, a common complaint during pregnancy. This may require treatment with antibiotics.
Gastrointestinal system
Pregnant women may suffer from bleeding gums. This could be due to hyperaemia of the gums as a result of which the gums swell and become spongy. There are indications that gingivitis occurs more often during pregnancy. Treatment consists of good dental hygiene. If an excessive amount of dental plaque is present, this should be removed.
One of the earliest subjective pregnancy symptoms is morning sickness (emesis gravidarum). The cause is probably hormonally (hCG) determined. The nausea makes it more difficult to swallow saliva as a result of which ptyalism appears to increase. Morning sickness is experienced by the majority of pregnant women and about 30% of all pregnant women suffer from vomiting. Even though this form of nausea and vomiting are physiological symptoms, they can cause the woman considerable inconvenience and they can also lead to work absenteeism.
Treatment should be conservative and consists of lifestyle and nutrition advice:
- eat a snack before getting up in the morning (dry cracker or slice of toast and a cup of tea) and then lie in bed for another half hour
- take frequent and light meals during the rest of the day
- take enough rest during the day.
By the 16th week of pregnancy emesis gravidarum should have disappeared.
During pregnancy gastrointestinal motility decreases, probably under the influence of the relaxing effect of progesterone. As a result of this pregnant women regularly experience functional insufficiency of the cardiac orifice and the food remains in the stomach longer. This results in nausea and heartburn due to reflux.
The treatment consists of lifestyle and dietary advice:
- frequent small meals, milk, and eating a small snack before going to sleep: avoid strongly-seasoned food
- avoid certain positions such as bending over and sleeping without a pillow.
The reduced intestinal motility, in particular the reduced peristalsis of the large intestine can cause constipation symptoms.
The treatment consists of lifestyle and dietary advice:
- increase daily fluid intake
- fibre-rich food
- fruit juice (prune juice, orange juice)
- sufficient physical exercise.
During pregnancy the absorption of water and electrolytes in the colon increases. This can lead to harder faeces which, in combination with constipation, can cause haemorrhoids.
Treatment consists of a fibre-rich diet. If necessary a haemorrhoids ointment containing lidocaine can be used as a painkiller. Eating habits can change markedly during pregnancy. The appetite increases during the second trimester in particular, once morning sickness has disappeared. Sometimes a pregnant woman will desire foods that she does not eat or scarcely eats outside of pregnancy. Even with a normal diet, a woman’s body will build up reserves during pregnancy long before these are needed by the foetus.
Sometimes the reserves are so large that the woman remains several kilos heavier after giving birth than she was before the pregnancy. In the case of a normal varied diet it is not necessary to ‘eat for two’ during pregnancy (see also section 3, ‘Information and recommendations for future parents’). Body weight increases by an average of 12 kg during pregnancy.
Musculoskeletal system
The connective tissue changes in composition and becomes more elastic, which is mainly seen in the sacroiliac joints and the symphysis. This can be viewed as a normal and beneficial preparation of the body for parturition. However, greater instability occurs in all joints which gives rise to an increased risk of overloading certain groups of muscles. As the uterus increases in size and hangs forwards slightly, the woman will increase her lumbar lordosis to remain in balance when walking. These changes sometimes cause lumbar backache.
The aetiology of calf cramps during pregnancy is not known. Calf cramps mainly occur during the second half of the pregnancy, in particular at night when the woman lies in bed. Treatment consists of massage and strong dorsal flexion of the foot and toes during which the knees and legs are kept straight. Women who also spontaneously develop calf cramps during the day should no longer swim in deep water due to the risk of drowning.
Skin
During pregnancy increased pigmentation of the skin occurs, particularly in the areolae of the breasts, the face (pregnancy mask) and the medial line under the navel. Sometimes blue-red stretch marks (striae) develop in the skin on the abdomen, hips, upper legs, and breasts.
During pregnancy the blood vessels dilate and proliferate. This can cause spider naevi to develop. Oestrogens are believed to be responsible for such changes, although there is no evidence to support this. In the absence of pregnancy, spider naevi are mainly seen during oestrogen therapy and in the case of liver diseases where the breakdown of oestrogens in the liver is significantly reduced. Small lesions disappear spontaneously once the cause has disappeared. Blood circulation in the skin increases as a result of which the skin feels warmer. Increased transpiration, erythema and a clammy feeling in the palms of the hands can occur.
Existing body hair increases somewhat and after pregnancy women sometimes notice an increased loss of hair. This phenomenon can be explained as follows: Hair follicles develop in a cyclical pattern. The hair growth cycle starts with the anagen (growth) phase of months to years, a short catagen (involution) phase and a telogen (resting) phase of several weeks (for the scalp). When a new cycle starts, the telogen hair is shed. On average, 10 to 15% of the hair follicles are in the telogen phase. Oestrogens at high doses delay the hair growth and extend the anagen phase, so that at the end of pregnancy only a few hair follicles enter the telogen phase. Moreover, oestrogens are thought to extend the telogen phase so that the overturn of new hair growth is postponed. Postpartum, after the strong decrease in the oestrogen level, the backlog of hair follicles in the end-anagen phase will enter both the catagen and telogen phases simultaneously and will subsequently be forced out by the initial growth of new hairs. In a short time (during the first five months postpartum) 50% of scalp hair can fall out, known as telogen effluvium. It should be explained to the patient that this is an overturn of new hair growth and not a permanent loss of hair. After a few months hair density will have recovered. The reason that pubic and axillary hair do not participate so visibly in this synchronous overturn of new hair growth, is related to the fact that the length of the hair growth cycle and the hormonal influence differs strongly per anatomical region. The average length of the anagen phase is, for example, 3 years for scalp hair and 3 months for facial hair.
Breasts
The breasts increase in size and feel tenderer, sometimes painful. This is caused by hyperaemia and hypertrophy of the gland tissue. These changes take place as a consequence of the increased concentration of oestrogens, progesterone, prolactin and human placental lactogen (hPL). Lactogenesis does not occur during pregnancy due to the inhibitory effect of oestrogens on milk secretion. Towards the end of the pregnancy an enhanced superficial venous pattern can be seen on the breasts, the areola becomes pigmented and the nipple becomes hypertrophic.
Psyche
In addition to the above-mentioned physical changes, many psychological changes occur. Apart from the positive experience of the pregnancy, there can be disquiet about a good outcome, irritation about the physiological side effects and a reduced interest in the outside world. Fear of damaging the foetus or of causing premature parturition sometimes has a negative effect on sexual relations. Good information and targeted advice can save the woman from a lot of inconvenience (see also section 3, ‘Information and recommendations for future parents’).