Analysis on birth status of small for gestational age infants in Beijing, 2011-2020

doi:10.3877/cma.j.issn.1673-5250.2023.03.006

Objective

To investigate the birth situation and relative influencing factors of small for gestational age (SGA) infants in Beijing in the past 10 years.

Methods

A total of 117 499 SGA infants borned in Beijing from January 2011 to December 2020 in "Beijing Neonatal Disease Screening and Management System" were selected as the research objects and a retrospective analysis was carried out. The incidence of SGA infants among premature, full-term and post-term infants were compared by chi-square test. The incidence of SGA infants in live births in the past 10 years was compared by trend chi-square test. Gestational age and birth weight (BW) of SGA infants in the past ten years were compared by trend test of variance analysis. Ordered multi-classification logistic regression analysis was used to analyze the influencing factors of gestational age (premature, full-term and post-term) of SGA infants. Influencing factors of the occurrence of severe SGA in SGA infants in Beijing was performed using multivariate unconditional logistic regression analysis. The procedures followed in this study were approved by the Ethics Committee of Beijing Obstetrics and Gynecology Hospital, Capital Medical University (Approval No. 2022-KY-091-01).

Results

①From 2011 to 2020, the incidence of SGA infants among live births in Beijing was 5.4%, the ratio of male to female SGA infants was 1.12∶1. The incidence of SGA among preterm infants was 8.2% (10 512/128 749), which were higher than that among term infants [5.2% (106 789/2 056 719)] and post-term infants [6.9% (198/2 868)], respectively, and the differences were statistically significant (χ²=2 107.78, 17.04; both with P<0.001); ②There was significant difference of overall comparison of SGA incidence in live births in the past 10 years from 2011 to 2020 (χ²=122.13, P<0.001), but no linear trend (χ²_trend=0.06, P=0.805). The gestational age and BW of SGA infants in the past 10 years showed a linear trend of decreasing with increasing of years. ③Compared to being full-term SGA infants after birth: the probability of multiple and male fetuses being preterm SGA (PT-SGA) infants after birth were 1.520 times (OR=1/0.658) and 2.261 times (OR=2.261) as much as single and female fetuses. The probability of fetus of female and born in winter being post-term SGA infants after birth were 3.021 times (OR=1/0.331) and 1.618 times (OR=1/0.618) as much as fetus of male and born in autumn.④Multiple fetus (OR=1.340, 95%CI: 1.285-1.400, P<0.001), male fetus (OR=1.267, 95%CI: 1.232-1.302, P<0.001), mother was registered in other citys (OR=1.052, 95%CI: 1.023-1.082, P<0.001), and preterm birth (OR=1.532, 95%CI: 1.464-1.602, P<0.001), were all independent risk factors for the development of severe SGA in SGA infants in Beijing from 2011 to 2020.

Conclusions

In 10 years, the incidence of SGA in live births in Beijing is lower than that in developed countries and our country. Attention should be paid to the management of risk factors of BW and gestational age of newborns in order to improve the quality of life of SGA infants.

Key words: Infant, small for gestational age, Birth weight, Premature birth, Pregnancy, multiple, Risk factors, Root cause analysis, Infant, newborn

表1 2011—2020年北京市10个年份出生的活产儿中SGA儿情况比较

年份(年)	活产儿数(例)	SGA儿发生率[例(%)]	SGA儿(±s)
年份(年)	活产儿数(例)	SGA儿发生率[例(%)]	出生胎龄(周)	BW(g)
2011	197 914	11 266(5.7)	38.7±1.6	2 562±318
2012	236 546	12 271(5.2)	38.6±1.6	2 550±327
2013	208 345	10 975(5.3)	38.6±1.6	2 551±329
2014	271 771	14 425(5.3)	38.6±1.6	2 551±333
2015	172 405	9 283(5.4)	38.5±1.7	2 533±344
2016	279 396	14 283(5.1)	38.5±1.7	2 542±340
2017	242 811	12 755(5.3)	38.4±1.7	2 533±347
2018	213 819	11 287(5.3)	38.3±1.7	2 525±347
2019	218 396	12 126(5.6)	38.4±1.7	2 531±344
2020	161 222	8 828(5.5)	38.3±1.7	2 530±339
统计量		χ²＝122.13	F＝11.81	F＝110.92
P值		<0.001	<0.001	<0.001

表1 2011—2020年北京市10个年份出生的活产儿中SGA儿情况比较

年份(年)	活产儿数(例)	SGA儿发生率[例(%)]	SGA儿(±s)
年份(年)	活产儿数(例)	SGA儿发生率[例(%)]	出生胎龄(周)	BW(g)
2011	197 914	11 266(5.7)	38.7±1.6	2 562±318
2012	236 546	12 271(5.2)	38.6±1.6	2 550±327
2013	208 345	10 975(5.3)	38.6±1.6	2 551±329
2014	271 771	14 425(5.3)	38.6±1.6	2 551±333
2015	172 405	9 283(5.4)	38.5±1.7	2 533±344
2016	279 396	14 283(5.1)	38.5±1.7	2 542±340
2017	242 811	12 755(5.3)	38.4±1.7	2 533±347
2018	213 819	11 287(5.3)	38.3±1.7	2 525±347
2019	218 396	12 126(5.6)	38.4±1.7	2 531±344
2020	161 222	8 828(5.5)	38.3±1.7	2 530±339
统计量		χ²＝122.13	F＝11.81	F＝110.92
P值		<0.001	<0.001	<0.001

表2 2011—2020年北京市3种类型PT-SGA儿的BW分布比较[例数(%)]

类型	例数	BW<1 000 g	1 000 g≤BW<1 500 g	BW≥1 500 g
早期PT-SGA儿	702	327(46.6)	375(53.4)	0
中期PT-SGA儿	1 199	43(3.6)	968(80.7)	188(15.7)
晚期PT-SGA儿	8 611	9(0.1)	499(5.8)	8 103(94.1)

表2 2011—2020年北京市3种类型PT-SGA儿的BW分布比较[例数(%)]

类型	例数	BW<1 000 g	1 000 g≤BW<1 500 g	BW≥1 500 g
早期PT-SGA儿	702	327(46.6)	375(53.4)	0
中期PT-SGA儿	1 199	43(3.6)	968(80.7)	188(15.7)
晚期PT-SGA儿	8 611	9(0.1)	499(5.8)	8 103(94.1)

表3 影响2011—2020年北京市SGA儿BW和出生胎龄的单因素分析结果

影响因素	例数	BW			出生胎龄
影响因素	例数	g，±s	统计量	P值	周，±s	统计量	P值
胎儿性别			t＝25.36	<0.001		t＝1.89	0.169
男	61 949	2 583±339			38.5±1.7
女	55 550	2 495±329			38.5±1.7
孕妇户籍			F＝7.31	0.001		F＝2.44	0.087
本市	74 912	2 544±329			38.5±1.6
外埠	42 091	2 536±351			38.5±1.8
外籍^a	496	2 556±336			38.6±1.7
妊娠胎数			F＝5 964.21	<0.001		F＝6 669.34	<0.001
单胎	104 016	2 585±309			38.7±1.6
多胎1	6 714	2 239±338			36.8±1.4
多胎2	6 714	2 182±359			36.7±1.5
多胎3	55	1 630±397			34.1±2.0
出生季节			F＝31.81	<0.001		F＝46.53	<0.001
春	29 894	2 541±337			38.5±1.7
夏	31 596	2 547±334			38.5±1.7
秋	29 793	2 550±333			38.5±1.7
冬	26 216	2 525±345			38.4±1.8
出生月份			t＝60.40	<0.001		t＝85.13	<0.001
寒冷月份	56 110	2 533±341			38.4±1.7
温暖月份	61 389	2 549±333			38.5±1.7

表3 影响2011—2020年北京市SGA儿BW和出生胎龄的单因素分析结果

影响因素	例数	BW			出生胎龄
影响因素	例数	g，±s	统计量	P值	周，±s	统计量	P值
胎儿性别			t＝25.36	<0.001		t＝1.89	0.169
男	61 949	2 583±339			38.5±1.7
女	55 550	2 495±329			38.5±1.7
孕妇户籍			F＝7.31	0.001		F＝2.44	0.087
本市	74 912	2 544±329			38.5±1.6
外埠	42 091	2 536±351			38.5±1.8
外籍^a	496	2 556±336			38.6±1.7
妊娠胎数			F＝5 964.21	<0.001		F＝6 669.34	<0.001
单胎	104 016	2 585±309			38.7±1.6
多胎1	6 714	2 239±338			36.8±1.4
多胎2	6 714	2 182±359			36.7±1.5
多胎3	55	1 630±397			34.1±2.0
出生季节			F＝31.81	<0.001		F＝46.53	<0.001
春	29 894	2 541±337			38.5±1.7
夏	31 596	2 547±334			38.5±1.7
秋	29 793	2 550±333			38.5±1.7
冬	26 216	2 525±345			38.4±1.8
出生月份			t＝60.40	<0.001		t＝85.13	<0.001
寒冷月份	56 110	2 533±341			38.4±1.7
温暖月份	61 389	2 549±333			38.5±1.7

表4 2011—2020年北京市SGA儿出生胎龄影响因素的有序多分类logistic回归分析结果

SGA儿出生胎龄^a	影响因素	B	SE	Wald值	ν	P值	OR值	OR值95%CI
早产	单胎儿(vs多胎儿)	－0.418	0.037	124.770	1	<0.001	0.658	0.612~0.708
	男性(vs女性)	0.816	0.037	494.960	1	<0.001	2.261	2.105~2.430
	母亲户籍(vs外籍)
	本市	0.224	0.310	0.522	1	0.470	1.252	0.681~2.300
	外埠	0.267	0.311	0.735	1	0.391	1.306	0.710~2.402
	出生季节(vs冬季)
	春	0.044	0.051	0.759	1	0.384	1.045	0.946~1.155
	夏	－0.470	0.051	0.860	1	0.354	0.954	0.864~1.054
	秋	－0.009	0.052	0.032	1	0.859	0.991	0.894~1.097
过期产	男性(vs女性)	－1.105	0.163	45.712	1	<0.001	0.331	0.240~0.456
	母亲户籍(vs外籍)
	本市	－1.850	0.727	6.471	1	0.110	0.157	0.038~0.654
	外埠	－0.095	0.716	0.018	1	0.895	0.910	0.223~3.703
	出生季节(vs冬季)
	春	－0.233	0.202	1.329	1	0.249	0.792	0.533~1.177
	夏	－0.113	0.193	0.343	1	0.558	0.893	0.611~1.304
	秋	－0.482	0.213	5.105	1	0.024	0.618	0.407~0.938

表4 2011—2020年北京市SGA儿出生胎龄影响因素的有序多分类logistic回归分析结果

SGA儿出生胎龄^a	影响因素	B	SE	Wald值	ν	P值	OR值	OR值95%CI
早产	单胎儿(vs多胎儿)	－0.418	0.037	124.770	1	<0.001	0.658	0.612~0.708
	男性(vs女性)	0.816	0.037	494.960	1	<0.001	2.261	2.105~2.430
	母亲户籍(vs外籍)
	本市	0.224	0.310	0.522	1	0.470	1.252	0.681~2.300
	外埠	0.267	0.311	0.735	1	0.391	1.306	0.710~2.402
	出生季节(vs冬季)
	春	0.044	0.051	0.759	1	0.384	1.045	0.946~1.155
	夏	－0.470	0.051	0.860	1	0.354	0.954	0.864~1.054
	秋	－0.009	0.052	0.032	1	0.859	0.991	0.894~1.097
过期产	男性(vs女性)	－1.105	0.163	45.712	1	<0.001	0.331	0.240~0.456
	母亲户籍(vs外籍)
	本市	－1.850	0.727	6.471	1	0.110	0.157	0.038~0.654
	外埠	－0.095	0.716	0.018	1	0.895	0.910	0.223~3.703
	出生季节(vs冬季)
	春	－0.233	0.202	1.329	1	0.249	0.792	0.533~1.177
	夏	－0.113	0.193	0.343	1	0.558	0.893	0.611~1.304
	秋	－0.482	0.213	5.105	1	0.024	0.618	0.407~0.938

表5 2011—2020年北京市SGA儿发生重度SGA影响因素的多因素非条件logistic回归分析结果

影响因素	B	SE	Wald值	P值	OR值	OR值95%CI
单胎儿(vs多胎妊娠儿)	—0.293	0.021	192.541	<0.001	0.746	0.716~0.778
男性(vs女性)	0.236	0.014	286.522	<0.001	1.267	1.232~1.302
母亲户籍(vs本市)
外埠	0.051	0.014	12.302	<0.001	1.052	1.023~1.082
外籍	0.061	0.106	0.334	0.563	1.063	0.863~1.309
出生季节(vs冬季)
春季	0.019	0.020	0.853	0.356	1.019	0.979~1.060
夏季	0.029	0.020	2.107	0.147	1.029	0.990~1.070
秋季	—0.011	0.020	0.282	0.596	0.989	0.951~1.029
出生胎龄(vs足月产)
早产	0.426	0.023	344.749	<0.001	1.532	1.464~1.602
过期产	0.250	0.161	2.401	0.121	1.283	0.936~1.760
常数项	—1.134		1 967.459	<0.001	0.322

表5 2011—2020年北京市SGA儿发生重度SGA影响因素的多因素非条件logistic回归分析结果

影响因素	B	SE	Wald值	P值	OR值	OR值95%CI
单胎儿(vs多胎妊娠儿)	—0.293	0.021	192.541	<0.001	0.746	0.716~0.778
男性(vs女性)	0.236	0.014	286.522	<0.001	1.267	1.232~1.302
母亲户籍(vs本市)
外埠	0.051	0.014	12.302	<0.001	1.052	1.023~1.082
外籍	0.061	0.106	0.334	0.563	1.063	0.863~1.309
出生季节(vs冬季)
春季	0.019	0.020	0.853	0.356	1.019	0.979~1.060
夏季	0.029	0.020	2.107	0.147	1.029	0.990~1.070
秋季	—0.011	0.020	0.282	0.596	0.989	0.951~1.029
出生胎龄(vs足月产)
早产	0.426	0.023	344.749	<0.001	1.532	1.464~1.602
过期产	0.250	0.161	2.401	0.121	1.283	0.936~1.760
常数项	—1.134		1 967.459	<0.001	0.322

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