Pregnancy (1)
Here we examine some data obtained mainly from ‘Nutrition during Pregnancy and Lactation’ produced by the Committee on Nutritional Status during Pregnancy (Washington, D.C.: National Academy Press, 1990).
A. Recommended range of weight gains
1) For women of normal weight (BMI 19.8 to 26) at beginning of pregnancy.
The gain in weight ranges from 25 pounds (11.36 kg) to 35 pounds (15.9 kg) obtained thus:
a) 5 pounds (2.27 kg) during the first three months
b) 1 pound (0.45 kg) per week subsequently
Variations over the range are as follows:
c) Adolescents should be at the upper end of the range because they are still growing
d) Women of height of 5 foot 2 inches (1.57 metres) or less should be at the lower end of the range.
2) For underweight women (BMI less than 19.8) [see http://incidentals.blog.co.uk]
The weight gains should range from 28 pounds (12.7 kg) to 40 pounds (18.2 kg)
3) For overweight women (BMI 26 to 29)
The weight gains should range from 15 pounds (6.8 kg) to 25 pounds (11.4 kg)
4) For obese women (BMI greater than 29)
The weight gains should be at least 13 pounds (6 kg).
Weight of infant at birth
For a total weight gain of 30 pounds (13.63 kg) this is about 7.5 pounds (3.4 kg).
C) Weight gain linked to increased fat stores
For a total weight gain of 30 pounds (13.63 kg) there is an increase in fat reserves of about 7 pounds (3.18 kg) or 24500 Calories i.e. (7 x 3500).
This is ear-marked mainly for labour and lactation.
D) Remaining components of weight gain
For a total weight gain of 30 pounds (13.63 kg), these may be listed as follows:
a) Placenta = 1.5 pounds (0.68 kg)
b) Increase in mother’s blood volume = 4 pounds (1.82 kg)
c) Increase in mother’s fluid volume = 4 pounds (1.82 kg)
d) Fluid to surround foetus = 2 pounds (1.82 kg)
e) Increase in size of uterus and supporting muscles = 2 pounds (1.82 kg)
f) Increase in size of breasts = 2 pounds (1.82 kg)
E) Weight loss after pregnancy
D (a) and (d) are lost at delivery.
In the weeks that follow more weight is lost as blood volume returns to normal and accumulated fluid is shed.
However retention of a couple of pounds (or so) after each pregnancy is usual among women even though their weight gains fall within the normal range.
Note that the weight retained by women who experience greater than ‘normal’ weight gains through pregnancy is invariably greater.
F) For women carrying twins
The gain in weight should range from 35 (15.9 kg) to 45 pounds (20.45 kg)
[Note:
a) If the weight gains in the earlier stages of pregnancy exceed the recommended quantities the energy intake should not be reduced in the later stages (in an attempt to achieve weight loss).
b) Sudden large weight gains require urgent medical investigation and intervention.]
