Influence of perinatal factors on full-term low-birth-weight infants and construction of a predictive model

Table 1 Single-factor analysis of full-term low-birth-weight, n (%)

Factor	Low-weight group	Normal group	t/χ2 value	P value
Maternal age (years) (mean ± SD)	28.24 ± 4.09	28.14 ± 4.39	0.685	0.495
Maternal education level			14.628	< 0.001
Junior high school and below	27 (43.55)	392 (22.63)
High school and above	35 (56.45)	1340 (77.37)
Frequency of prenatal examination (times) (mean ± SD)	10.01 ± 0.35	10.57 ± 0.39	8.278	< 0.001
Weight gain during pregnancy
Insufficient	37 (59.68)	119 (6.87)	210.361	< 0.001
Suitable	21 (33.87)	1412 (81.52)
Overweight	4 (6.45)	201 (11.61)
Calcium supplementation during pregnancy			15.232	< 0.001
Rule	13 (20.97)	798 (46.07)
Irregularity	49 (79.03)	934 (53.93)
Pregnancy hypertension syndrome			12.162	< 0.001
Yes	9 (14.52)	81 (4.68)
No	53 (85.48)	1651 (95.32)
Gestational diabetes			0.548	0.459
Yes	7 (11.29)	254 (14.67)
No	55 (88.71)	1478 (85.33)
Pregnancy complicated with thyroid disease			0.254	0.614
Yes	4 (6.45)	87 (5.02)
No	58 (93.55)	1645 (94.98)
Fetal distress			1.386	0.239
Yes	8 (12.90)	149 (8.60)
No	54 (87.10)	1583 (91.40)
Premature rupture of membranes			2.547	0.110
Yes	6 (9.68)	88 (5.08)
No	56 (90.32)	1644 (94.92)
Oligohydramnios			2.968	0.085
Yes	5 (8.06)	65 (3.75)
No	57 (91.94)	1667 (96.25)
Gestational weeks at delivery (weeks) (mean ± SD)	38.43 ± 0.96	38.72 ± 1.13	1.515	0.132
Neonatal sex			2.882	0.090
Male	22 (35.48)	804 (46.42)
Female	40 (64.52)	928 (53.58)

Table 2 Results of multivariate logistic regression analysis

Variable	β	SE	χ2	P value	OR (95%CI)
Low level of maternal education	0.348	0.134	6.744	0.012	1.416 (1.058–2.975)
Low number of prenatal examinations	1.067	0.282	14.316	< 0.001	2.907 (1.893–6.278)
Insufficient weight gain during pregnancy	1.307	0.329	15.782	< 0.001	3.695 (2.092–7.455)
Irregular calcium supplementation during pregnancy	0.563	0.204	7.617	0.009	1.756 (1.146–3.984)
Pregnancy hypertension syndrome	0.785	0.226	12.065	< 0.001	2.192 (1.423–5.159)
Constant	−29.164	6.574	19.680	< 0.001	-

Table 3 Predicted and actual values of the model

Model prediction results	Actual results		Total	Sensitivity	Specificity	Accuracy
	LBW infants	Normal-birth-weight infants
LBW infants	10	53	63
Normal-birth-weight infants	2	235	237
Total	12	288	300	83.33	81.59	81.67

LBW: Low-birth-weight.