Psychological factors of pregnant women associated with inadequate maternal weight gain in Japan

Figures & data

Table 1. Recommended GWG according to the MHLW guideline in 2006.

Pre-pregnancy BMI	Recommended GWG
BMI < 18.5	9–12kg
BMI ≥ 18.5, and <25	7–12kg
BMI ≥ 25	Customized (Upper limit 5kg)

BMI: body mass index; MHLW: Ministry of Health, Labor and Welfare Japan; GWG: gestational weight gain.

Table 2. Characteristics of participants in the inadequate GWG and adequate GWG groups (n = 128).

		GWG
		Inadequate 23 (18.0%)	Adequate 105 (82.0%)
Variables	All	Mean ± SD or n (%)		p
Demographic variables
Pre-pregnancy body mass index				.014^a
<18.5 kg/m^2 (Underweight)	21 (16.4)	8 (34.8)	13 (12.4)
≥18.5, and <25 kg/m^2 (Normal)	107 (83.6)	15 (65.2)	92 (87.6)
Weeks of gestation (weeks)	27.0 ± 5.9	27.0 ± 6.5	27.0 ± 5.8	.985^b
Age (years)	33.1 ± 4.4	31.8 ± 4.1	33.4 ± 4.4	.139^b
20's	31 (24.2)	10 (43.5)	21 (20.0)	0.030^a
30's	87 (68.0)	13 (56.5)	74 (70.5)
40's	10 (7.8)	0 (0.0)	10 (9.5)
Parity (primiparas)	69 (53.9)	12 (52.2)	57 (54.3)	.854^a
Education (college graduate) (n = 127)	108 (85.0)	19 (86.4)	89 (84.8)	.547^a
Annual household income (≥9 million yen) (n = 119)	60 (50.4)	7 (33.3)	53 (54.1)	.084^a
Smoking before pregnancy (yes)	5 (3.9)	0 (0.0)	5 (4.8)	.296^a
Smoking during pregnancy (yes)	0 (0.0)	0 (0.0)	0 (0.0)
Nausea during first trimester (yes)	123 (96.1)	23 (18.7)	100 (95.2)	.365^a
Vomiting during first trimester (yes)	44 (34.4)	9 (39.1)	35 (33.3)	.596^a
Hospitalization for hyperemesis (yes)	2 (1.6)	2 (8.7)	0 (0.0)	.032^a
Complications (yes)
Gestational diabetes mellitus (yes)	0 (0.0)	0 (0.0)	0 (0.0)
Hypertensive disorders of pregnancy (yes)	1 (1.0)	0 (0.0)	1 (1.0)	.638^a
Intention of weight management
Have a target for GWG (yes)	92 (71.9)	18 (78.3)	74 (70.5)	.452^a
Target GWG (kg) (n = 92)	8.7 ± 1.6	7.9 ± 1.4	8.9 ± 1.6	.017^b
Thoughts of weight control during pregnancy
I do not want to gain much weight	42 (33.1)	4 (17.4)	38 (36.5)	.077^a
I want to gain as much weight as recommended by the guideline	70 (55.1)	13 (56.5)	57 (54.8)	.881^a
I want to gain as much weight as possible	1 (0.8)	1 (4.3)	0 (0.0)	.181^a
Not conscious about weight	14 (11.0)	5 (21.7)	9 (8.7)	.080^a
Psychological variables
Body Appreciation Scale-2 (BAS-2) score (n = 127)	31.0 ± 8.0	26.5 ± 8.7	31.9 ± 7.5	.003^b
Mother-Infant Bonding Questionnaire (MIBQ) score (n = 125)	4.0 ± 3.0	4.0 ± 3.7	3.9 ± 2.8	.817^b
Sense of Coherence-3 (SOC-3) Score	16.0 ± 3.1	15.5 ± 3.3	16.1 ± 3.1	.415^b
Edinburgh Postnatal Depression Scale (EPDS) score (n = 127)	4.7 ± 3.4	6.3 ± 4.0	4.4 ± 3.1	.009^b
Weight during pregnancy
Lost more weight during pregnancy compared with that before pregnancy (yes) (n = 127)	43 (33.9)	15 (65.2)	28 (26.9)	<.001^a
Maximum weight loss during pregnancy (kg)	1.7 ± 1.6	1.9 ± 0.5	1.3 ± 1.2	.026^b
Min – Max (kg)	0.1 – 7.0
Weeks when body weight decreased compared to that before pregnancy (weeks) (n = 43)	11.2 ± 1.4	11.7 ± 1.8	11.0 ± 1.1	.162^b
Weeks where body weight decreased to the maximum (weeks) (n = 42)	11.7 ± 2.0	12.5 ± 1.9	11.3 ± 1.8	.063^b
Weeks where body weight returned to above that before pregnancy (weeks) (n = 41)	18.8 ± 4.8	21.8 ± 5.3	17.0 ± 3.5	.001^b
Neonatal data
Birth weight	3010 ± 313	2888 ± 297	3037 ± 311	.038^b
Low birth weight (<2500g)	4 (3.1)	2 (8.7)	2 (1.9)	.148^a
Health belief
Perceived susceptibility (have a perception)
Excess GWG	59 (46.1)	7 (30.4)	52 (49.5)	.096^a
Inadequate GWG (n = 127)	10 (7.9)	5 (21.7)	5 (4.8)	.017^a
Perceived severity (have a perception)
Severity < miscarriage> (n = 125)	64 (51.2)	14 (60.9)	50 (49.0)	.304^a
Severity < LBW> (n = 127)	106 (83.5)	17 (73.9)	89 (85.6)	.146^a
Severity < children’s lifestyle related diseases> (n = 124)	53 (42.7)	8 (34.8)	45 (44.6)	.393^a
Perceived benefits (have a perception)
Benefits < baby health> (n = 127)	108 (85.0)	22 (95.7)	86 (82.7)	.098^a
Benefits < complication prevention> (n = 127)	115 (90.6)	21 (91.3)	94 (90.4)	.626^a
Benefits < recognize effort> (n = 125)	35 (28.0)	6 (26.1)	29 (28.4)	.821^a
Perceived barriers[eating] (have a perception) (n = 126)	90 (71.4)	18 (78.3)	72 (69.9)	.422^a
Barriers[exercise] (have a perception) (n = 123)	89 (72.4)	15 (65.2)	74 (74.0)	.396^a
Self-efficacy for healthy eating scale (n = 127)	27.5 ± 7.1	26.5 ± 8.3	27.6 ± 6.8	.529^b
Have confidence	28 (21.9)	6 (26.1)	22 (21.0)	.590^a
Cue to action < get advice from medical staff>	70 (54.7)	13 (56.5)	57 (54.3)	.845^a
Do not become overweight	35 (27.3)	1 (4.3)	34 (32.4)	.006^a
Gain more weight	6 (4.7)	4 (17.4)	2 (1.9)	.010^a
Do not gain too much and do not gain too little	16 (12.5)	3 (18.8)	13 (12.4)	.581^a
Specific values of GWG were presented	19 (14.8)	5 (21.7)	14 (13.3)	.233^a
Behavior < reduce intake of high calorie food>	93 (72.7)	15 (16.1)	78 (74.3)	.377^a
Behavior < increase intake of low calorie food>	97 (75.8)	15 (65.2)	82 (78.1)	.192^a
Behavior < physical activity>				.351^a
Increase	17 (13.3)	2 (11.8)	15 (14.3)
Decrease	7 (5.5)	0 (0.0)	7 (6.7)
Not change	50 (39.1)	12 (52.2)	38 (36.2)
Do nothing	54 (42.2)	9 (39.1)	45 (83.3)

GWG: gestational weight gain; BMI: body mass index; SD: standard deviation; ^aChi-square test; ^bStudent’s t-test.

Adequate GWG: pre-pregnancy BMI < 18.5 kg/m²: 9–12 kg/ pre-pregnancy BMI ≥ 18.5, and <25 kg/m²: 7–12 kg.

Table 3. Participants’ characteristics and delivery details in the inadequate GWG and adequate GWG groups according to pre-pregnancy BMI (n = 128).

	Pre-pregnancy body mass index <18.5kg/m^2 (underweight) n = 21					Pre-pregnancy body mass index ≥18.5, and <25kg/m^2 (normal) n = 107
	All	Inadequate GWG 8 (38.1%)	Adequate GWG 13 (61.9%)	p	Effect size	All	Inadequate GWG 15 (14.0%)	Adequate GWG 92 (86.0%)	p	Effect size
Variables	Mean ± SD or n (%)					Mean ± SD or n (%)
Have a target GWG (yes)	11 (52.4)	6 (75.0)	5 (38.5)	.119^b	1.760^d	81 (75.7)	12 (80.0)	69 (75.0)	.479^a	1.038^d
Target GWG (kg)	8.7 ± 1.4	8.3 ± 1.4	9.2 ± 1.4	.320^b	.638^c	8.7 ± 1.6	7.7 ± 1.4	8.9 ± 1.6	.019^b	0.752^c
Hospitalization for hyperemesis (yes)	1 (4.8)	1 (12.5)	0 (0.0)	.381^a	N.A.	1 (0.9)	1 (6.7)	0 (0.0)	.142^b	N.A.
Get advice from medical staff (yes)	9 (42.9)	4 (50.0)	5 (38.5)	.472^a	1.299^d	61 (57.0)	9 (60.0)	52 (56.5)	.801^a	1.062^d
Do not become overweight (yes)	2 (9.5)	0 (0.0)	2 (15.4)	.371^a	N.A.	33 (30.8)	1 (6.7)	32 (34.8)	.022^a	.193^d
Gain more weight (yes)	2 (9.5)	1 (12.5)	1 (7.7)	.629^a	1.623^d	4 (3.7)	3 (20.0)	1 (1.1)	.008^a	18.182^d
Do not gain too much and do not gain too little (yes)	2 (9.5)	1 (12.5)	1 (7.7)	.629^a	1.623^d	14 (13.1)	2 (13.3)	12 (13.0)	.621^a	1.023^d
Specific values of GWG were presented (yes)	2 (9.5)	1 (12.5)	1 (7.7)	.629^a	1.623^d	17 (15.9)	4 (26.7)	13 (14.1)	.192^a	1.894^d
Weight during pregnancy
Lost more weight during pregnancy compared with that before pregnancy (yes)	7 (33.3)	5 (62.5)	2 (15.4)	.041^a	2.750^d	36 (34.0)	10 (66.7)	26 (28.6)	.004^a	1.286^d
Weeks where body weight returned to above that before pregnancy (weeks)	20.0 ± 7.5	22.4 ± 7.6	14.0 ± 1.4	.069^b	1.230^c	18.5 ± 4.2	21.5 ± 4.1	17.3 ± 3.6	.005^b	1.125^c
Min–Max (weeks)	13.0 – 32.0					11.0 – 28.0
Gestational weight gain (kg)	9.1 ± 2.4	6.7 ± 1.9	10.6 ± 1.1			9.0 ± 2.2	4.5 ± 1.8	9.6 ± 1.3
Min–Max	3.1 – 12.0					1.0 – 12.0
Gestational weeks of pregnancy at birth	38.7 ± 1.2	38.9 ± 1.8	38.6 ± .6	.706^b	.214^c	39.0 ± 1.1	38.7 ± 1.0	39.1 ± 1.1	.270^b	0.309^c
Neonatal data
Child gender (boy)	6 (28.6)	3 (37.5)	3 (23.1)	.410^a	0.312^d	49 (45.8)	9 (60.0)	40 (43.5)	.234^b	.911^d
Birth weight (g)	2933 ± 273	2864 ± 296	2975 ± 260	.378^a	.405^c	3026 ± 319	2901 ± 308	3046 ± 318	.103^b	0.457^c
Low birth weight (<2500g)	0 (0.0)					4 (3.7)	2 (13.3)	2 (2.2)	.094^a	1.748^d
Birth height (cm)	49.1 ± 1.5	49.0 ± 1.2	49.2 ± 1.7	.849^b	.087^c	49.4 ± 1.6	49.0 ± 1.6	49.4 ± 1.6	.355^b	0.259^c
Birth chest circumference (cm)	31.8 ± 1.2	31.8 ± 1.4	31.9 ± 1.1	.813^b	.108^c	31.7 ± 1.4	31.8 ± 1.1	31.8 ± 1.4	.983^b	0.006^c
Birth head circumference (cm)	33.2 ± 0.9	33.2 ± 0.8	33.2 ± .9	.263^b	.055^c	33.2 ± 1.1	33.1 ± 1.7	33.2 ± 1.0	.825^b	0.090^c

GWG: gestational weight gain; BMI: body mass index; SD: standard deviation; ^aChi-square test; ^bStudent’s t-test; ^cCohen’s d; ^drelative risk.

Adequate GWG: pre-pregnancy BMI < 18.5 kg/m²: 9–12 kg/ pre-pregnancy BMI ≥ 18.5, and <25kg/m²: 7–12 kg.

Pre-pregnancy BMI < 18.5 kg/m²: n = 11 for target GWG, n = 7 for weeks where body weight returned to above that before pregnancy.

Pre-pregnancy BMI ≥ 18.5, and <25kg/m²: n = 81 for Target GWG, n = 34 for weeks where body weight returned to above that before pregnancy.

Data availability statement

The data that support the findings of this study are available from the corresponding author, M. H., upon reasonable request.