It's a dilemma. You feel fine and you want to carry on working as long as you can - but could you be harming your unborn baby? Or you feel tired and sick and struggle to keep up at work, but you don't want to be stuck at home twiddling your thumbs.

So when should mums-to-be give up work?

Friends, co-workers and family will all be offering pregnancy advice to you. But you have to listen to what your own body is telling you.

For some women the time to stop working is when they can't fit behind their desk or the driving wheel of their car. For others it's much earlier.

Ask yourself are you:

Losing steam in the middle of the day?
Restless nights could affect your daytime performance and cause you to be slow, grumpy or forgetful.

Stressing?
Worrying about all the preparations you have yet to do at home before your baby arrives.

Downright uncomfortable?
Is it uncomfortable to stand or sit for too long? Backache, swollen legs and feet, and breathlessness are all indications that you should be taking it easier.

Having labour signs?
Persistent aching in your lower back, cramping or spotting should never be ignored. You may be going into premature labour and your GP will most likely recommend complete bed rest.

According to a recent study, carrying on working after the eighth month of pregnancy results in women having babies of a lower birth weight.

The University of Essex research found that mums-to-be who continued to work up until their due date gave birth to babies an average of.5 pounds (230 gms) lighter than babies born to women who stopped working between months six and eight.

Babies with low birth weights are at higher risk of poor health and slow development, and may suffer from a variety of problems later in life.

The study drew a worrying parallel between these working women and those who smoked in pregnancy and also had lower birth weight babies.

However this study did not take into account the type of jobs the mums-to-be carried out. It's obvious that those doing more physical jobs and standing up for longer periods will have different results to women who work in a job where they are sitting for long periods or are able to take rest breaks.

If you really want to carry on working as long as possible talk to your doctor or midwife about your job and talk to your employer to see if certain allowances can be made. Perhaps they can arrange for you to have shorter more regular breaks, provision of a rest area, a more comfortable chair, or a stool to sit on instead of standing too long?

If you are the boss then be kinder to yourself!

But at the end of the day whatever pregnancy advice you are given, listen to your body and try to arrange for what you need for a comfortable pregnancy.