Week by week: Pregnancy - week 20

Well done! By the end of the week you'll be halfway through your pregnancy, as dated from your last period.

This may be the week of your anomaly scan when you'll get to see your baby on screen again, discover your baby's sex if you want to – and receive reassurance that your baby's development is on track.

Remember that in a minority of pregnancies, developmental abnormalities can be detected at this stage. Early detection gives the best outcome and provides expectant parents a chance to come to terms with any potential problems.

Inside story

Your baby's crown-to-rump length is around 15cm (6 inches) which is about the same height as a can of lager. Your baby has put on another 60g this week, bringing his weight up to around 260g (9oz) – just 10g heavier than a pat of butter.

The digestive system is becoming more sophisticated with each passing week and your baby can now utilize some of the nutrients contained in your amniotic fluid.

On the outside

Subtle changes are taking place that you might notice: an increase in skin pigmentation means you might see a faint (or, in some women pronounced) line running from your pubic bone up to your belly button: this is called a linea nigra and will disappear after the birth.

You'll notice your nipples becoming darker – and they won't change back after the birth.

You might find your bum and thighs expanding as your pelvis broadens, and you'll certainly notice more growth bump-wise!

Your breasts will be larger than they were pre-pregnancy, so don't forget to have regular bra fittings and to choose cotton, non-wired bras with wide, supportive straps and a deep hook band. This will help to minimise you'll minimize back and neck pain too.

Things to think about

You might not want to dwell on your pelvic floor, the girdle of muscles beneath your pelvis, but it's an essential muscle that you will need to familiarise yourself with. You can work them by contracting your anus (there's no nice way of saying it!) and by trying to stop yourself mid-wee.

Pelvic floor muscles help to prevent stress incontinence after pregnancy (where a small amount of wee escapes when you put your bladder under stress through lifting, coughing, sneezing or laughing). They can also help to retain muscle tone in your vagina so that your enjoyment of sex (and your partner's) isn't impaired.

You can practice pelvic floor exercises any time, any place – just watch out that you're not grimacing with concentration, as this is a dead giveaway!

• Imagine you're trying to stop yourself weeing, then gently pull this set of muscles up as tight as you can: your anus should contract at the same time.

• To get the timing and intensity right, imagine your pelvic floor muscles as a lift moving up from one floor to the next as you tighten them.

• Hold the squeeze for a few seconds, then relax the muscles gradually as you take the lift back down to the ground floor.

• Do as many repetitions as you can – and practice as often as possible. You can do them sitting, standing or lying down, so there aren't any excuses. All women should really do pelvic floor exercises every day of their lives.

Soft-boiled eggs 'now safe for pregnant women and babies'

Pregnant women and babies have been given the all-clear to eat soft-boiled eggs – and they could even prevent children developing allergies, according to a new study.

The British Egg Industry Council (BEIC) said the launch of a strict code of practice 15 years ago has been so successful that salmonella has been 'effectively eliminated', with 90 per cent of British eggs now laid by salmonella-vaccinated hens.

Each egg is stamped with a lion mark and a best-before date on the shell.

NHS Choices still advises pregnant women to avoid eating soft-boiled eggs, or giving them to babies after weaning because of the salmonella risk.

And just a fraction of babies are given eggs at six months because of allergy concerns.

But according to a new review published in the Journal of Health Visiting, nutritionist Dr Juliet Gray, said mothers may be unwittingly putting their children at greater risk of allergy by an avoidance strategy.

She said research suggests delayed introduction of potential food allergens, such as eggs, during weaning may actually be counterproductive.

In contrast the introduction of these foods while breastfeeding, between the ages of 4-7 months, could protect against developing allergies to these foods.

Dr Gray said two trials are being carried out to test whether the approach works and two government committees are also reviewing the current advice on infant feeding and food allergy.

She said "Eggs are highly nutritious, containing key nutrients including high quality protein, vitamin D, selenium, choline and omega-3 fatty acids, several of which are not found in many other foods.

"Our review concluded that mums and their babies can be encouraged to eat eggs, as this could have a positive effect in terms of nutritional intake and may also help immune tolerance of eggs.

"The BEIC advice that vulnerable groups can go back to runny eggs, if produced under the Lion scheme, should further reassure women that they can enjoy them normally in pregnancy and give them to their babies when weaning from six months."

A nationwide salmonella scare in 1988 – sparked by Edwina Currie who was health minister at the time – resulted in vulnerable groups such as expectant mums, infants and the elderly being advised not to eat undercooked eggs.