Evaluating the application of the 2009 Institute of Medicine gestational weight gain guidelines on pregnant Chinese women

Figures & data

Figure 1. Flowchart of the inclusion and exclusion criteria of the study.

Figure 2. Distribution of body mass index categories before pregnancy.

Figure 3. Weight gain in pregnant women under Institute of Medicine recommendations.

Table 1. Baseline characteristics of the included women and their infants (n=20 593).

Characteristic
Maternal age (years), mean±SD	32.36±3.94
Maternal height (cm), mean±SD	162.84±5.01
Pre-pregnancy weight (kg), mean±SD	58.23±9.32
Gestational weight gain (kg), mean±SD	13.85±4.99
Gestational weeks, mean±SD	38.85±1.68
Pre-pregnancy BMI category n(%)
Underweight (<18.5 kg/m^2)	2522(12.2%)
Normal (18.5-24.9kg/m^2)	14811(71.9%)
Overweight (25.0-29.9 kg/m^2)	2672(13%)
Obesity (≥30.0 kg/m^2)	588(2.9%)
Mode of delivery n(%)
Cesarean section	6656 (32.3%)
Vaginal delivery	13937 (67.7%)
Parity n(%)
Nulliparity	14529(70.6%)
Multiparity	6064(29.4%)
Newborn sex n(%)
Girls	9895(48.1%)
Boys	10698(51.9%)
Gestational age classification n(%)
SGA	1034 (5.0%)
AGA	15961 (77.5%)
LGA	3598 (17.5%)
Length of newborn (cm), mean ±SD	49.99±2.04
Weight of newborn (g), mean ±SD	3345.72±489.28

SD, standard deviation. SGA, small for gestational age. AGA, appropriate for gestational age. LGA, large for gestational age.

Table 2. The incidence of adverse pregnant outcomes under the standard of 2009 IOM guideline.

Prepregnancy BMI category	No.(%)	Cesarean section	Preterm birth	SGA	LGA
Underweight (n=2522)
Insufficient	699(27.7%)	146(20.9%)**	69(9.9%)**	69(9.9%)*	54(7.7%)**
Adequate	1303(51.7%)	242(18.6%)**	33(2.5%)**	104(8%)*	110(8.4%)**
Excessive	520(20.6%)	141(27.1%)**	11(2.1%)**	27(5.2%)*	83(16%)**
Normal (n=14811)
Insufficient	4055(27.4%)	1169(28.8%)**	320(7.9%)**	250(6.2%)**	504(12.4%)**
Adequate	6448(43.5%)	1909(29.6%)**	271(4.2%)**	285(4.4%)**	1028(15.9%)**
Excessive	4308(29.1%)	1558(36.2%)**	130(3%)**	182(4.2%)**	941(21.8%)**
Overweight (n=2672)
Insufficient	365(13.7%)	141(38.6%)*	52(14.2%)**	23(6.3%)*	65(17.8%)**
Adequate	891(33.3%)	364(40.9%)*	71(8%)**	36(4%)*	212(23.8%)**
Excessive	1416(53%)	671(47.4%)*	93(6.6%)**	37(2.6%)*	431(30.4%)**
Obesity (n=588)
Insufficient	115(19.6%)	51(44.3%)*	23(20%)*	5(4.3%)	26(22.6%)
Adequate	215(36.6%)	110(51.2%)*	18(8.4%)*	7(3.3%)	64(29.8%)
Excessive	258(43.9%)	154(59.7%)*	22(8.5%)*	9(3.5%)	80(31%)

GWG, gestational weight gain. BMI, body mass index. LBW, low birth weight. SGA, small for gestational age. LGA, large for gestational age.

*, p<0.05; **, p<0.001

Figure 4. Risk curves under different body mass index categories. Underweight (a), Normal weight (b), Overweight (c), and Obese (d).

Table

ID:□□□□□ Medical record number: ______________ Name: _______Age (years): _______Occupation: _______ Pre-pregnancy body weight (kg): _______ Maternal height (m): _______ Telephone number: _______ Last menstrual period: _______ Date of delivery: _______ Gestational age: _______ Pre-delivery body weight (kg): _______ Parity: _______ Length of the newborn (cm): ________ Weight of newborn (g): _______ Newborn sex: _______ Apgar score: 1-minute:_______5-minute: _______10-minute: _______ Amount of postpartum hemorrhage: _______ Mode of delivery: □Cesarean section □Vaginal delivery

Table

Categories	Cesarean section	Preterm birth	SGA	LGA	Combined risk
Underweight	Y=exp(−1.641 + 0.021 x)	Y=exp(−0.866 – 0.016 x)	Y=exp(−1.716 –0.050 x)	Y=exp(−3.066 + 0.054x)	Y = 0.000537x^2 – 0.017247x + 0.481669
Normal	Y=exp(−1.169 + 0.027 x)	Y=exp(−1.759 – 0.092 x)	Y=exp(−2.523 –0.033 x)	Y=exp(−2.408 + 0.055x)	Y = 0.000519x^2 – 0.009448x + 0.479481
Overweight	Y=exp(−0.646 + 0.033 x)	Y=exp(−1.873 – 0.048 x)	Y=exp(−2.758 –0.046 x)	Y=exp(−1.801 + 0.062x)	Y = 0.000091x^2 + 0.004888x + 0.531713
Obese	Y=exp(−0.326 + 0.053 x)	Y=exp(−1.472 – 0.080 x)	Y=exp(−3.146 –0.017 x)	Y=exp(−1.236 + 0.037x)	Y = 0.000386x^2 + 0.000068 x + 0.653351

SGA, small for gestational age; LGA, large for gestational age.