Food And Growth

New babies need as much breast milk or properly made formula as they willingly drink and the offer of some cooled boiled water a couple of times each day. They do not need anything else until they are at least three months old.

Once the birthweight has been regained at around ten days old the baby will gain weight at around 1oz (28g) per day. Of course there will be day-to-day variations, but he will average 6-8oz (170-225g) each week.

Many parents find it difficult to leave it entirely to the baby to decide how much milk to take. They feel a great need to know exactly what he "ought" to have so that they can be sure he is having enough. But feeding a baby is not an exact science because babies vary just as much as older people in their food needs. A baby with a slow, efficient metabolism will have plenty of energy and grow well on fewer calories than a baby who burns his food up faster and less completely.

More adults are bad at adjusting their food intake to suit their individual metabolisms. Our eating is mixed up with habit, social customs and pure greed. But a small baby's adjustment is almost always perfect, at least until we confuse it for him by introducing solid foods. Whatever quantities your baby takes, you can be quite sure that they are right for him provided he is offered as much as he wants whenever he wants it; he is contented most of the time and becoming more contented as he gets older and more settled; he is active whenever he is awake and becoming more so with age and he gains weight steadily at somewhere near that expected 6-8oz (170-225g) each week.

If your baby is bottle-fed you may want to know approximately how much milk he is likely to want - if only so that you can organize your shopping. It is usually reckoned that babies should have about 3oz (85ml) of milk for each pound of their bodyweight offered to them during an average 24-hour period. That means around 21oz (595ml) for a 7lb (3.2kg) baby and around 27oz (765ml) for a 9lb (4.1kg) baby. But don't let those figures affect your feeding. The baby can have more if he wants it and will often take less. Remember that if he were breast-fed you would not know how much he'd had.

Expected Weight Gain

If you find yourself worrying about your baby's weight gain or you want a scientific way of supporting your own observations of his or her abundant good health, you need to understand the importance of the rate of weight gain we expect and therefore of your baby's expected or ideal weight.  

Your baby's birthweight is his personal starting point for growth. Whatever that birthweight was, he will grow roughly the same amount and at approximately the same rate as all other babies. His overall growth follows a pre-set trajectory rather like a rocket which, once launched, follows a pre-determined pattern. You fuel his growth with proper food and adequate care and as long as you do so the upward growth curve will be steady. If illness, starvation, serious neglect or emotional disturbance should lead his weight gain to dip downward off that expected curve, he will need an extra boost of food-energy to put him back on course. If over-concentrated bottles or concealed cereals should lead his weight gain to peak upward off his personal curve, he will need the milk reduced to its proper composition so that he can get back on course. 

So a baby needs to be fed, always, according to his expected weight. If he has gained much less than average, feeding him as if he had gained normally will give him the chance to gain fast for a while. If he has gained very fast, feeding him as if he had not will give him the chance to slow his rate of gain for a while. Of course if he is being fed on demand, with neither restriction nor forcing, he will see to this for himself. But if his food is limited by a scanty breast milk supply or strict scheduling, or if it is pushed on him by an over-strong formula or too-early solids, he may not be able to make the adjustment for himself. Assuming that the weight the scales tell you that he is equals the weight he is meant to be could lead you into a vicious circle of misfeeding. Let's look at how this might happen in practice.

Imagine that your baby was born weighing 7lb (3.2kg) but was ill after birth, lost more weight than average and now, in his third week, is being bottle-fed and weighs 6lbs (2.7kg). If you accepted that 6lbs (2.7kg) actual weight as normal for him you might assume that six times 3oz (85ml) would meet his needs in each 24 hours, offer him that much, be pleased when he drank it all and then horrified to find that he was not gaining weight. The point is that that baby's expected weight is not 6lbs (2.7kg) but around 8lbs (3.6kg) so that 18oz (510ml) of milk could not possibly be enough. He needs to be offered around 24oz (680ml) and to be allowed to drink as much of it as he wants. 

Calculating your Baby's Expected Weight

Height or Length Matter, Too

Weight gain is not the only way to assess a baby's growth. Children are not meant to get fatter but bigger overall. Getting taller (or longer) matters, too. Your baby's length will change much more slowly than the weight and it is far more difficult to measure accurately, but whatever your baby's length at birth, approximately 3/4 in (2cm) will be gained each month or just over 2in (5cm) in three months.

Just as there is an expected weight for a baby of any age, related to birthweight, so there is an expected length at any age, related to birth-length. A complete record of your baby's growth means charting both measurements together. You will find that if all is going well, the two will rise in a consistent relationship to each other.  

Changes and Exceptions to Normal Growth Patterns

Babies do not continue to grow at the same rate as each other forever. We interfere with the regularity of growth by overfeeding or underfeeding, or introducing solid foods early or late. Life interferes too, making one child subject to many infections and another resistant to them. Eventually the child's own hormones interfere: the pre-puberty growth spurt takes place at different times and rates in different people. But for most babies the pattern shown on the Growth Charts will be the norm for at least the first year and often for the first three years.

The most common exceptions are premature babies. They may be very slow to get started with feeding and therefore with growing. They may do no more than hold their low position, relative to average babies, for a long time. 

Small-for-dates babies may make startling growth during their early weeks, especially if they were partly starved in the womb. With excellent care such babies may change position from the very bottom of the lowest section of the chart to somewhere near the top of that "small baby" section.

Babies who are ill immediately after birth or in their first weeks may fail to start gaining weight or may actually lose some. Again excellent care may lead to a spurt of "catch up growth" so that the baby's personal growth curve shifts upwards and then settles down on the new, higher trajectory.

Babies who are bottle-fed from birth may lose no weight in the first days. They may even gain very fast from the beginning, especially if the formula is made too strong or they are encouraged to take a set amount. An even greater rise in such a baby's weight curve may be seen if solid foods are added early to the full quota of over-concentrated milk. It is in a case like this that the importance of recording length as well as weight becomes clear: a baby who is gaining weight faster than nature intended will not gain length to match it. The disparity is your cue that your child is getting obese rather than simply growing large.

"Average" is Easier

Society is geared to average babies. If your baby was not of average birthweight you need to be aware of it and allow for the difference. Baby clothes which are sized by age may mislead you. A stretch suit for "birth to three months" means 7-12lbs (3.2 - 5.5kg) and length to match. It will not last your ten pounder for long. Over-the-counter medicines still occasionally advise dosage by age rather than weight and that can be extremely misleading. A small baby needs less of any medicine than a larger one. 

Above all, don't be taken in by the various "sayings" about weight gain which you may hear quoted as gospel truth. This one, for example: "A baby should double his birthweight by six months and triple it by a year." Well, should yours? If you look at the Growth Chart you will see that the average birthweight boy in the middle will indeed double his birthweight in six months and triple it in a year, but the small baby at the bottom will almost double his in three months and triple it in six. If he gained "by the saying," he would be half starved. As for the big baby at the top, while his birthweight may indeed double by six months it will be nowhere near tripled by a year. If he gained "by the saying," he would be grossly fat.