Maternal Anatomical and Physiological Changes in Pregnancy

What hormone stimulates respiration, relaxes smooth muscle of blood vessels, uterus and gut, increases body temperature and increases sodium and chloride excretion?

What hormone is responsible for promoting growth of the endometrium and breasts, enhances myometrial activity, increases sensitivity to carbon dioxide, increases prolactin secrection, stimulates fluid retention, alters the composition of connective tissue and increases uterine sensitivity to progesterone in late pregnancy

What hormone is responsible for softening of the ligaments of the pelvis?

What hormone is responsible for increasing maternal metabolism and utilisation of fat as an energy substrate?

The size and the weight of the uterus [blank_start]increases[blank_end] in response to various stimuli and stretching of the uterus by fetal growth promotes synthesis of contractile proteins of the [blank_start]myometrium[blank_end]. As the uterus expands it loses its anteverted and [blank_start]anteflexed[blank_end] configuration, becoming erect, tilted and rotated to the right under pressure of the descending [blank_start]colon[blank_end]. By 20 weeks gestation the uterine fundus is at the level of the [blank_start]umbilicus[blank_end] and the uterus is an ovoid shape. By 30 weeks gestation the enlarging uterus has displaced the intestines laterally and superiorly so the caecum and appendix are at the iliac crest. The [blank_start]abdominal[blank_end] wall supports the uterus and maintains the relation between the long axis of the uterus and the axis of the pelvic [blank_start]inlet[blank_end]. The uterus falls back and rests on the vertebral column, inferior [blank_start]vena cava[blank_end] and aorta when in the [blank_start]supine[blank_end] position. The uterine isthmus increases and forms the lower uterine segment, low-intensity [blank_start]Braxton Hicks[blank_end] contractions causes it to shorten in preparation for cervical dilatation.

[blank_start]Oestrogen[blank_end] increases blood supply to the cervix, which increases in mass and width, resulting in a lilac colouration and softer tissue texture. [blank_start]Increased[blank_end] blood flow to the vagina results in softer tissue of the vagina walls, as the mucosa thickens, the connective tissue loosens and smooth muscle cells hypertrophy, in preparation for [blank_start]distension[blank_end] during labour. Vaginal [blank_start]secretions[blank_end] increase, under the influence of oestrogen, resulting in a thick, white discharge called [blank_start]leucorrhoea[blank_end]. Simple personal hygiene, wearing [blank_start]cotton[blank_end] pants and avoiding tights can increase comfort. Vaginal acidity increases due to [blank_start]increased[blank_end] activity and proliferation of vaginal flora, lactobacillus acidophilus, in response to high levels of [blank_start]oestrogen[blank_end]. This helps to protect women from [blank_start]gential tract infections[blank_end] in pregnancy, which may lead to perinatal complications.

Candida albicans is a bacterial infection.

The heart displaces [blank_start]upwards[blank_end] and rotates forwards by the elevation of the [blank_start]diaphragm[blank_end]. The size of the heart [blank_start]increases[blank_end] by 12% in response to increased filling and cardiac muscle hypertrophy, stimulated by oestrogen. increased blood volume increases [blank_start]venous[blank_end] return which increases atrial size and contractibility. [blank_start]Cardiac output[blank_end] increases by 30-50%, by an average of 1.5l/min. [blank_start]Blood volume[blank_end] increases due to a rise in plasma volume, by 40-50%, and red cell mass. However the rise in red cell mass is not matched by the rise in plasma volume so [blank_start]haemoglobin[blank_end] level is reduced, resulting in [blank_start]physiological anaemia[blank_end].

Cardiac output is sensitive to changes in posture during pregnancy

Lying in what position can affect cardiac output

The effect of progesterone on smooth muscle can increases incidents of fainting in pregnancy

NICE guidelines (2014) recommends the consideration of iron supplementation for haemoglobin levels of..... at 28 weeks gestation

Oedema and varicose veins of in the legs, vulva and anus is attributed to decreased blood flow, decreased venous return and increased venous pressure.

Pregnancy is associated with major changes in the respiratory system, in lung volume and ventilation. By the end of pregnancy 16-20% more oxygen is consumed to meet the increased metabolic needs of the maternal body and fetoplacental unit. In the [blank_start]upper[blank_end] respiratory tract, the nasopharynx mucosa becomes more hyperaemic and oedematous with hypersecretion of mucus, caused by [blank_start]oestrogen[blank_end]. this can result in nasal [blank_start]stuffiness[blank_end] and more common occurrence of [blank_start]epistaxis[blank_end]. There are changes in the shape of the chest due to relaxation of muscles and cartilage. the [blank_start]diaphragm[blank_end] is displaces upwards, by 4cm, and there is an increase in the [blank_start]diameter[blank_end] of the chest, by 2cm. Flaring of the [blank_start]ribs[blank_end] also increases the substernal angle, in late pregnancy, from 68 degrees to 103 degrees. Breathing changes from abdominal to [blank_start]thoracic[blank_end], with increased diaphragmatic movement. Maternal pulmonary [blank_start]ventilation[blank_end] increases by 40%, due to the effects of [blank_start]progesterone[blank_end] lowering sensitivity of chemoreceptors for carbon dioxide. As a result the respiratory drive is stimulated at lower [blank_start]carbon dioxide[blank_end] levels so pregnant women are able to breath more [blank_start]deeply[blank_end]. Tidal volume, the amount of air passing in and out of the lungs in each respiratory cycle, increases, thus increasing minute ventilation by 40%, this hyperventilation increases [blank_start]oxygen.[blank_end] consumption.

What is dyspnoea?

During pregnancy the urinary system is altered. The kidneys [blank_start]enlarge[blank_end] and lengthen due to increased [blank_start]blood flow[blank_end] and vascular volume. Glomerular size increases and the glomerular filtration [blank_start]rate[blank_end] increases by 40-50%, in a 24 hour period the volume of urine produced [blank_start]increases[blank_end] by 25%. The rise in glomerular filtration rate raises the amount of fluid and solutes present within the tubules by 50-100%. Therefore tubular [blank_start]reabsorption[blank_end] must increase to prevent the loss of sodium, chloride, glucose, potassium and water. However the tubular reabsorption rate may not accommodate the increased load so substances such as glucose and amino acids are [blank_start]excreted[blank_end]. In the later half of pregnancy, the ureters elongate, become more [blank_start]tortuous[blank_end] and are displaced by the gravid uterus. The may hold up to 25% more urine. There is an increased risk of [blank_start]urinary tract infections[blank_end] due to these changes.

Glucosuria, glucose in urine, always indicates gestational diabetes

Proteinuria, protein in the urine, is associated with pre eclampsia

What happens to the capacity of the bladder in pregnancy?

What other factors increase the risk of urinary tract infections?

Increased urinary output leads to what?

Urinary incontinence becomes more prevalent during pregnancy

Oestrogen and progesterone causes the gums to become highly vascularised, oedematous and spongy, which may lead to what?

Progesterone is an appetite stimulant

What is pica?

[blank_start]Progesterone[blank_end] impairs the tone of the lower oesophageal [blank_start]sphincter[blank_end], contributing to the [blank_start]reflux[blank_end] of gastric contents into the lower oesophagus, leading to [blank_start]heartburn[blank_end]. This can be limited by having more frequent but smaller meals, avoidance of spicy, fatty, seasoned food and avoidance of lying horizontally or bending forwards. NICE guidelines (2014) recommends lifestyle and diet modification to alleviate heartburn. However if it persists despite changes to lifestyle and diet, antacids may be offered. In the second and third trimester of pregnancy, progesterone and the pressure of the gravid uterus on the rectosigmoid colon decreases [blank_start]motility[blank_end] of the small intestine and colon transit time is [blank_start]increased[blank_end]. This may result in bloating, constipation and [blank_start]haemorrhoids[blank_end]. Again NICE (2014) recommends diet modification to incorporate more [blank_start]fibre[blank_end]. Standard haemorrhoid creams can be used if symptoms remain troublesome.

What is ptyalism?

The weight of the gravid uterus leads to a shift in the centre of [blank_start]gravity[blank_end], which alters the inclination of the pelvic [blank_start]brim[blank_end]. Lordosis of the spine occurs, due to the effects of progesterone, [blank_start]relaxin[blank_end] and increased uterine weight, to compensate for the shift in the centre of gravity. This could result in muscle and ligament strain and/or [blank_start]backache[blank_end]. The effect of relaxin on the symphysis pubis and the sacroiliac joints increases [blank_start]flexibility[blank_end] and mobility of the pelvis. This results in the rolling waddling gait when walking and can cause [blank_start]pelvic girdle pain[blank_end].

Leg cramps are common in the third trimester of pregnancy

Sleep patterns change in pregnancy

What can be caused by compression of nerves and blood vessels?

Progesterone and oestrogen increases the production of melanocyte-releasing hormone from the anterior pituitary gland. This stimulates [blank_start]pigmentation[blank_end] in pregnancy. Hyperpigmentation of the linea alba, a line that lies over the midline of the rectus muscles from the umbilicus to the symphysis pubis, cause the appearance of [blank_start]linea nigra[blank_end]. Deposition of melanin causes pigmentation of the face, known as [blank_start]chloasma[blank_end]. Increasing maternal size results in the stretching of the collagen layer of the skin, particularly over the breasts, abdomen and thighs. this could result in [blank_start]striae gravidarum[blank_end].