Preface

1 Scope

This standard specifies the recommended value of weight gain of natural singleton pregnancy in China.

This standard is applicable to guide weight gain in Chinese women.

This standard is not apply to women with height below 140 cm or weight higher than 125 kg before pregnancy.Patients with comorbidities and complications during pregnancy should be evaluated individually in combination with clinical opinions.

2 Normative references

There are no normative references available in this standard.

3 Terms and definitions

The following terms and definitions apply to this standard.

3.1 Pregnancy period

It is approximately 280 days (40 weeks) from the first day of the last menstrual period.

Note: The whole course of pregnancy is clinically divided into three periods: first trimester, second trimester and third trimester.

3.2 First trimester

First trimester is the first 13 weeks long of a pregnancy (＜ 14 weeks).

3.3 Second trimester

Second trimester includes weeks 14 through 27 of a pregnancy (27+6weeks).

3.4 Third trimester

Third trimester includes weeks 28 through 40 of a pregnancy.

3.5 Body mass index; BMI

An index of body weight is calculated as the ratio of body weight (kg) to the square of body height (m).

3.6 Pre-pregnancy weight

Mean body weight during the three months before pregnancy.

3.7 Pre-delivery weight

The last weight weighed in the week before delivery.

3.8 Gestational weight gain, GWG

GWG refers to pre-delivery weight (kg) minus pre-pregnancy weight (kg).

3.9 Gestational weight gain in first trimester

Weight at the end of the 13th week of gestation (kg) was calculated by subtracting pre-gestation weight(kg).

3.10 Gestational weight gain in second trimester

Weight at 27 weeks of gestation (kg) was subtracted from weight at 13 weeks of gestation (kg).

3.11 Gestational weight gain in third trimester

Weight before delivery (kg) was subtracted weight at 27 weeks of gestation (kg).

4 The range of weight gain and the recommended weekly weight gain in the second and third trimester of pregnancy

According to the cut point of Chinese BMI, the recommended range of weight gain and weekly weight gain of the second and third pregnancy pregnant women under different pre-pregnancy BMI was given respectively,as shown in Table 1.

5 Measurement methods

The height and weight of pregnant women are measured in Appendix A.

Appendix A

Measurement of height and weight of pregnant women

A.1 Height measurement

A.1.1 Measurement conditions

Pregnant women should be bareheaded, barefoot, and untie the braid, with room temperature of about 25 °C.

A.1.2 Measurement tool

Stadiometer (height meter, accuracy of 0.1 cm) with wall offset device is used.The slide plate should be perpendicular to the beam and slide freely.

A.1.3 Measurement method

Pregnant woman stands up straight on the pedal, inhale deeply and hold breath, natural arms drooping,heels close, and toes about 60 degrees apart.The knees are straight together, the eyes are straight ahead, and the lower edge of the orbit remains at the same level as the upper edge of the auricle.Three points between the heel, hip and the two shoulder blades contact the vertical beam at the same time, keeping the head upright.The measuring person move the headpiece gently down until it is in contact with the head vertex,when the value is read after observing the pregnant woman’s correct posture.

A.1.4 Reading numbers and records

When reading, the eyes of the meter are on the same horizontal surface as the bottom surface of the slide measuring plate.Read the value shown by the column corresponding to the bottom surface of the slide measuring plate, which is accurate to 0.1 cm.

A.2 Body weight measurement

A.2.1 Measurement conditions

The measurement should be carried out in the morning, empty stomach and excretion, at room temperature of about 25 °C.A.2.2 Measurement tool

A calibrated electronic scale with a score of 0.1 kg was stable and zero during measurement.

A.2.3 Measurement method

Pregnant women are calmly standing in the middle of the scale pedal, even weight on both legs,bareheaded and barefoot, wearing thin underwear and paying attention to safety.

A.2.4 Reading numbers and records

The scale readings were accurately recorded, accurate to 0.1 kg.