Oxford Handbook of Midwifery by Janet Medforth, Sue Battersby, Maggie Evans, Beverley Marsh, Angela Walker

cause of backache and ligament pain.
Skin changes
Increased pigmentation of the areola, abdominal midline, perineum, and axillae due to a rise in pituitary melanin-stimulating hormone.
The ‘mask of pregnancy’, or chloasma, a deeper colouring of the face, develops in 50–70% of women, is more common in dark-haired women, and is exacerbated by sun exposure.
Striae gravidarum, commonly called stretch marks, occur as the collagen layer of the skin stretches over areas of fat deposition, e.g. breasts, abdomen, and thighs.
The stretch marks appear as red stripes and change to silvery white lines within 6 months of delivery.
Scalp, facial, and body hair become thicker. The excess is shed in the postnatal period.
The breasts
Breast changes are one of the first signs of pregnancy noticed by the mother. From around 3–4 weeks’ gestation there is increased blood flow and tenderness, veins become more prominent, and the breasts feel warm.
Under the influence of oestrogen, fat is deposited in the breasts, increasing their size. The lactiferous tubules and ducts enlarge.
The pigmented area around the nipple darkens.
CHAPTER 4 Antenatal care
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Progesterone causes growth of the lobules and alveoli, and develops the secretory ability of these structures, ready for lactation.
Prolactin stimulates the production of colostrum from the second trimester onwards, and after delivery is responsible for the initiation of milk production.
The endocrine system
All the endocrine organs are influenced by secretion of placental hor- mones during pregnancy.
Pituitary hormones : prolactin, adrenocorticotropic hormone (ACTH), thyroid hormone, and melanocyte stimulating hormone (MSH) increase. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are inhibited. Oxytocin is released throughout pregnancy and increases at term, stimulating uterine contractions.
Thyroid hormones : total thyroxine levels rise sharply from the second month of pregnancy. The basal metabolic rate is increased.
Adrenal hormones : cortisol levels increase, leading to insulin resistance and a corresponding rise in blood glucose, particularly after meals. This
makes more glucose available for the fetus.
Pancreas : due to increasing insulin resistance, the B cells are stimulated
to increase insulin production by up to four times during pregnancy. In women with borderline pancreatic function, this may result in the development of gestational diabetes, affecting 3–12% of pregnant women.
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CHAPTER 4 Antenatal care
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Blood values in pregnancy
Table 4.1 summarizes the main components of the blood and shows the values prior to pregnancy and the changes as a result of the maternal adaptation to pregnancy.
The main feature is physiological anaemia due to increased plasma volume despite a rise in the red cell mass.
Decreasing plasma protein concentrations lead to lower osmotic pressure contributing to the oedema seen in the lower limbs during pregnancy. Moderate oedema when not associated with disease is an indicator of a favourable pregnancy outcome.
Table 4.1 The main components of blood
Component
Non-pregnant
Change in pregnancy
Plasma volume
2600mL
3850mL at 40 weeks
Red cell mass
1400mL
1650mL at 40 weeks
Total blood volume
4000mL
5500mL at 40 weeks
Haematocrit (PCV)
35%
30% at 40 weeks
Haemoglobin
12.5–13.9g/dL
11.0–12.2g/dL at 40 weeks
Protein
65–85g/L
55–75g/L at 20 weeks
Albumin
35–48g/L
25–38g/L at 20 weeks
Fibrinogen
15–36g/L
25–46g/L at 20 weeks
Platelets
150–400 x 10 3+ /mm 3
Slight decrease
Clotting time
12min
8min
White cell count
9 × 10 9 /L
10–15 × 10 9 /L
Red cell count
4.7 × 10 12 /L
3.8 × 10 12 /L at 30 weeks

THE BOOKING INTERVIEW
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The booking interview
The booking interview is a holistic assessment of the woman’s social, health, educational, and psychological needs and identifies those needing additional care. The purpose of the interview is to obtain a history and exchange