Unit 2B The practice of human biology The relevance of human biology to everyday life Pregnancy.

Unit 2BThe practice of human biology

The relevance of human biology to everyday life

Pregnancy

Further information

Further information about this topic can be found in Our Human Species (3rd edtn)

Chapter 15, sections 1-3 Chapter 16 , section 9-12

Diet

• Doctors recommend that there is no need to eat more food during pregnancy; rather, pregnant women should concentrate on diet quality rather than quantity

• During pregnancy there is a greater need for certain nutrients, such as iron and folate, but only a small amount of extra energy is needed

Pregnant woman eating fresh salad, bread and cheese

Anthea Sieveking, Wellcome Images

The food pyramid

Diet and nutrition, fruit and vegetables

Fiona Pragoff, Wellcome Images

A balanced diet

Eat mostly:– fruit and vegetables – wholegrain breads and cereals

Eat moderately: – low fat dairy foods e.g. low fat milk, cheese and

yoghurt– lean meats, chicken or fish

Eat least: – foods high in sugar e.g. sweets, cakes, biscuits, soft

drinks – foods high in fat e.g. margarine, butter, oil and cream– foods high in salt

Calories

• Pregnant women do not need to eat for two – they should concentrate on diet quality rather than quantity

• During the second and third trimesters, energy requirements increase by about 600 kJ a day . This can be covered by increasing fruit intake from 2 serves to 4 serves

A pregnant woman checking her weight

Anthea Sieveking, Wellcome Images

• A normal weight gain over the course of the pregnancy is around 10–13 kg.Most of this is:– the baby ~3 kg – the muscle layer of the uterus ~1 kg – the placenta ~600 g – extra breast weight ~400 g – extra blood volume ~1.2 kg– amniotic fluid ~2.6 kg

• During a pregnancy there may be a need for certain nutrients, such as iron and folate.

• If the woman is eating a balanced diet there is usually no need for extra vitamins (too much vitamin A can be dangerous) or calcium.

Folic acid (folate)• Folic acid is one of the B vitamins.• If a woman has a deficiency of folic acid

during pregnancy there is an increased risk of having an underweight baby or a baby with a neural tube defect (e.g. spina bifida). There is also a greater risk of suffering a miscarriage.

• If a woman is planning to become pregnant it is recommended that she take folic acid for at least one month before, to three months after conception.

Good dietary sources of folic acid

Asparagus Chickpeas Parsley

Bran flakes Dried beans Peas

Broccoli Leeks Spinach

Brussels sprouts Lentils Wheatgerm

Cabbage Oranges Wholegrain bread

Cauliflower Orange juice

Folic acid is recommended for pregnant mothers to reduce the risk of spina bifida in their unborn babies

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IRON

• During pregnancy some women suffer a shortage of iron and become anaemic.

• The growing baby, the placenta and the extra red blood cells in the mother’s bloodstream all require extra iron.

• Vitamin C helps absorb iron.

• Iron supplements can cause constipation.

Substances pregnant women should avoid

• NO– Alcohol– Tobacco– Illegal drugs (e.g. cannabis, cocaine)– Uncooked meats– Foods containing unpasteurised milk (e.g. soft or blue

cheeses)– Foods containing raw egg

• REDUCED AMOUNTS OF– Fish that might be high in mercury, e.g. shark,

swordfish, Spanish mackerel– Caffeine

Listeria

• Listeria is a relatively uncommon infectious illness caused by the bacterium Listeria monocytogenes.

• In pregnant women, a listeria infection usually has mild, flu-like symptoms.

• However, the illness can lead to miscarriage, stillbirth or premature birth.

Dodgy foods• Soft cheeses e.g. brie, blue cheese, fetta • Pate • Foods containing unpasteurised milk• Cold meats • Dried/fermented sausages • Raw or smoked sea foods e.g. oysters, sushi • Prepared and pre-packed salads • Soft serve ice-cream

• The bacterium responsible for listeria is destroyed by heat, so it is best to thoroughly cook all foods

Toxoplasmosis

• Toxoplasmosis is a fairly rare infectious illness caused by the parasite, Toxoplasma gondii.

• In adults, a toxoplasmosis infection usually has mild, flu-like symptoms.

• However, the illness can lead to miscarriage, stillbirth or serious birth defects.

• The toxoplasmosis parasite is usually carried in cat faeces and uncooked meat.

Anthea Sieveking, Wellcome Images

• The only thing worse than a smoke-filled room is a smoke-filled womb.

Smoking• Carbon monoxide crosses the placenta

and affects the oxygen supply to the baby.

• There may also be some damage to the genes of the developing baby.

• Smoking is associated with placental complications, increased risk of miscarriage, stillbirths, growth retardation, low birth weight, SIDS (Sudden infant death syndrome), respiratory problems, asthma and other illnesses.

Alcohol

• Babies whose mothers drink alcohol during pregnancy are at risk of developing fetal alcohol syndrome.

• Alcohol can affect the development of the brain at any stage of the pregnancy.

• Doctors recommend that pregnant women avoid alcohol altogether.

Symptoms of FAS

• Babies with fetal alcohol syndrome (FAS) generally – are below average height and weight – develop slowly – display a number of abnormal facial features – show signs of varying degrees of mental

retardation – experience behavioural problems.

Doctors recommend that pregnant women should not drink alcohol

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Pharmaceuticals

• Some pharmaceutical products can be dangerous during pregnancy .

• Pregnant women should always seek the advice of a doctor before taking medicines.

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Cannabis sativa

• Babies exposed to cocaine and cannabis during pregnancy are more likely to have learning or behaviour problems when they are older.

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Study Guide

Read:• Our Human Species

Chapter 15, sections 1-3

Chapter 16, sections 9-12

Complete:• Workbook

Topic 19 - Pregnancy