Does size matter? No, not that! Is your baby too fat, too thin, is she eating too much or not enough? Not only have you got your weight to worry about, now there's two of you!

In the first week your baby will lose weight, about 5-8% of her birth weight. Don't be alarmed, this is perfectly natural. She built up a store of fat to help her cope with the birth and the first few days before your breastmilk kicks in, and her digestive system needs a bit of time to get used to life outside the womb. She will probably reach her birth weight at 2 or 3 weeks and will continue to grow.

You will have been given a Red Book after the birth and in there you will find centile charts. There are separate charts for boys and girls, and for weight, length (height) and head circumference. Each chart is split into centiles, the 50th centile running through the middle (the average), and the 10th and 91st centiles at the outer boundaries. Each time you visit your local clinic your health visitor will measure baby to see how much she has grown, and the measurements will be plotted on the charts. If her measurements fall below the 50th centile, she is smaller than average; above and she is larger than average.

Centile charts are just guidelines and, while her chart will probably rise and follow her particular centile, there will be occasional blips. Again, this is nothing to worry about. She may have a growth spurt, or a pause or even a fall if she is ill and off her food or she doesn't take readily to solids. Then when she starts to crawl and walk, she will burn off more calories and start to lose her baby shape.

There is no 'right' size for a baby, they come in all shapes and sizes, just like adults. As long as she is feeding well and is healthy, how much weight she has gained in the last week or so is not important.

If baby doesn't gain weight for two or three months, this is known as 'failure to thrive'. Other symptoms will be apparent during this period, like refusing her milk or poor feeding and general lethargy. Failure to thrive is rare - less than one baby in a hundred is affected.

Ensure that you regularly attend your baby clinic. Your baby's growth and general health will be monitored by experts and any questions or worries you have will be answered.