There is a lot of information about ideal weight gains in pregnancy.  This page is only addressing the issue humbly with some principles.

Many references put optimal weight gain in the whole pregnancy as between 20 to 25 lb.  Body weight may actually go down or stay steady in the first 3 months (13 weeks) when appetite is poor.  In the next 6 months or 27 weeks, morale and appetite both improves and weight usually increases rapidly, unless there is voluntary restraint, or the baby is growing slowly without causing positive effect on the mother.  Therefore it is advisable that a pregnant lady gains only around 1 lb each week.  Rarely, the mother does not gain weight in between weeks, it may be seen as a reflection about need to look into welfare, but the weight itself may not be that important if the baby is found to be growing well.

I usually explain to mothers the reduction in weight at time of childbirth.

The average newborn weighs 7 lb, and it is very unusual for a child to weigh 3 lb more to 10 lb.

The placenta weighs about 1 lb.  The amniotic fluid measures about 500 cc, and therefore another 1 lb.

There is going to be blood loss of 1 to 2 lb.

Water redistribution allows about 2 lb of water to be passed out as urine.

The overall weight loss is going to be about 12 lb.  At the most, the baby weighs 2 to 3 lb more and water loss of another lb is sort of upper limit.  If blood loss goes beyond a litre (2 lb), there is replacement by the doctor so as to be safe.  So a mother cannot lose more than another 4 to 5 lb.

It is now understandable that any weight gain above 12 to 16 lb goes to tissues of the mother, not the baby or matter which is shed off at childbirth.

An excess of 10 lb or so is expected to shed off during the next month in relation to breast feeding and work.  The author explains a catch here, frequently seniors of the family cook a lot of food for the new mother as tonic.  The social pressure often makes the lady gain a lot of weight in the several weeks before she returns to work.

It may be useful to understand some norms for the Chinese in HK in order to manage appropriate weight of the mother.

In traditional Chinese culture, a mother is asked to aim towards twice her appetite, because she ‘has to eat on behalf of the baby’.  This is in fact not necessary.  Everyone likes to eat, and usually young ladies limit their food intake before pregnancy in order to keep their shape.  When this rule is lifted and the appetite is good, as in the middle and final thirds of pregnancy, the lady may gain weight with uncontrolled momentum.

It is advisable that an expecting lady keeps a chart of her body weight, e.g., by the week, and post it onto somewhere convenient.  The door of the refrigerator (place to keep food) is a possible starting point.  She ha.  s an idea how her habits influence her weight, and there is some bio-feedback.

Food is very important.  It is usually sound advice that she needs protein and calories.  The former is obtained usually from a diverse source of meat.  Calories is usually obtained from staple food such as rice.  In addition, it is very important to have a lot of vegetables.  Fibre intake may be increased because bowel muscles are weaker and it is easy to develop into constipation.  The lady may distinguish between vegetables (fibre and a little water) and fruit (a lot of water plus a little fibre).   Fruit juice is actually solution of fructose (fruit sugar) in water with various flavour pleasant to our mouth, and does not help with dietary need or passage of waste directly.

In HK, where food from many sources and places of origin is available, it may be most useful to balance supplies with rotating intake from various sources.  For example, it is always right to have apple, pear, orange on rotation between days.  Similarly, rotation between pork, chicken, fish and other meat, imported from China, Australia, Thailand, etc.

Recently, there is recommendation that fish meat can be taken, but not too much.  The skin of fish is not usually taken together.   Fish intestines and internal organs are also not consumed.

Concentrated soup, e.g., ‘double boiled’ prepared as it is described, is not the best source of water and nutrients in early pregnancy, when the lady is vomiting a lot and water is particularly necessary to maintain balance.  Lightly prepared soup is however a good and tasty choice.