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1 ORIGINAL ARTICLE Korean J Obstet Gynecol 2012;55(5): pissn eissn PREGNANCY PROGNOSIS ACCORDING TO PREPREGNANCY BODY MASS INDEX AND GESTATIONAL WEIGHT GAIN IN TWIN PREGNANCIES Myung Joo Kim, MD 1, Eun Duc Na, MD 1, Kyoung Jin Lee, MD, PhD 1, Dong Hyun Cha, MD, PhD 1, Joong Sik Shin, MD, PhD 1, Hwa Young Lee, MD, PhD 2 Departments of 1 Obstetrics and Gynecology, 2 Internal Medicine, CHA Gangnam Medical Center, CHA University College of Medicine, Seoul, Korea Objective To analyze the pregnancy outcome and prognosis related to prepregnancy body mass index () and gestational weight gain in twin pregnancies according to the 2009 Institute of Medicine recommendation. Methods The study subjects were 500 twin pregnant women and their 1,000 babies delivered from January 2008 to December The women divided in 4 groups according to prepregnancy ; underweight (<18.5 kg/m 2 ), normal weight (18.5 <23 kg/m 2 ), overweight (23.0 <25 kg/m 2 ), and obese ( 25 kg/m 2 ) and also categorized 3 groups according to gestational weight gain; poor if it was below the IOM range for the prepregnancy, normal if it was within the range, and excessive if it was above the range. Results Among total 500 twin pregnant women, underweight were 76 (15.2%), normal weight 330 (66.0%), overweight 55 (11.0%) and obese 39 (7.8%); poor 237 (47.4%), normal 220 (44%) and excessive 43 (8.6%). The mean total weight gain during pregnancy was 16.3±4.9 kg and mean weight gain per week was 0.45±0.13 kg/wk. Gestational diabetes mellitus was significantly associated with obese women. Anemia was significantly increased in poor weight gain group whereas gestational hypertension, large for gestational age and neonatal score of 5 minutes under 7 were significantly increased in excessive weight gain group. Conclusion The adverse pregnancy and neonatal prognosis were associated with abnormal prepregnancy or gestational weight gain in twin pregnancies. It is important to maintain normal prepregnancy and gestational weight gain through appropriate counseling and education. Keywords: Twin pregnancy; ; Maternal weight gain; Pregnancy outcome 임신전체질량지수 (body mass index, ) 와임신중산모의체중증가정도는산모의건강유지와정상적인태아발달을위하여필수적이며, 산모의예후에영향을줄뿐만아니라태아의성장과발달및신생아의예후에영향을미친다는많은국내외보고가있다. 임신중체중증가가부족한경우조산아또는부당경량아출생, 주산기합병증의증가와관련이있다고하였고 [1,2], 체중증가가과다한경우에는부당과량아출생, 신생아의인공호흡기치료, 저체온증, 저혈당, 태변흡인증후군, 제왕절개술빈도증가, 임신성고혈압, 임신성당뇨, 난산등과관련되어있다고알려져있다 [3,4]. 이러한양상은쌍태임신에서도마찬가지로나타날뿐아니라쌍태임신은단태임신에비해임신성고혈압, 조 Received: Revised: Accepted: Corresponding author: Kyoung Jin Lee, MD, PhD Department of Obstetrics and Gynecology, CHA Gangnam Medical Center, CHA University College of Medicine, 566 Nonhyeon-ro, Gangnam-gu, Seoul , Korea Tel: Fax: jlee3575@chamc.co.kr This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright Korean Society of Obstetrics and Gynecology 300

2 Myung Joo Kim, et al. Pregnancy prognosis in twin pregnancies 산, 부당경량아, 자궁내태아성장지연등의비율이높고신생아의질병이환율과주산기사망률또한증가하는것으로보고되었다 [5]. 따라서단태임신및쌍태임신모두에서임신중체중증가량에대한주의는적절한상담과식이, 운동등을통해체중증가량을조절함으로써임신예후에긍정적영향을미칠수있다는점에서중요하다. 이러한일환으로 2009년 Institute of Medicine [6] 에서는이전데이터를분석하여임신전체질량지수를기준으로임신중적절한체중증가정도를제시하여단태임신및쌍태임신각각에대해새로운권고안을발표한바있다. 최근보조생식술의발달과시술의보편화로인해전체출생중쌍태아출산의비율은 1991 년 0.99%, 2000년 1.68%, 2010 년 2.73% 로증가하는추세 [7] 에있으나국내임신부를대상으로임신전체질량지수와임신중체중증가를함께고려한쌍태임신예후및신생아의주산기예후와관련된전반적인연구는아직까지부족한실정이다. 따라서본연구에서는 2009 년새로개정된 IOM 의권고사항을토대로쌍태임신부의임신전체질량지수및임신중체중증가량에따른산모의임신예후및신생아의주산기예후에중점을두어전반적인임신결과를살펴보고자한다. 2008년 1월부터 2010년 12월까지강남차병원에서분만한쌍태임신산모 500명및이들이분만한신생아 1,000명을대상으로의무기록을조사하여후향적으로연구를시행하였다. 동질한집단을연구대상으로하기위해외국인산모를제외한한국인산모만을대상으로하였고, 당뇨, 고혈압등만성적인내과력이있는산모는제외하였으며, 쌍태아중한명이상의자궁내태아사망이있는경우, 선천성기형이있거나쌍태아간수혈증후군이있는경우도연구대상에서제외하였다. 그밖에의무기록상산모의임신전키, 체중, 분만시체중및신생아기록이불완전한경우역시제외하였다. 임신주수는최종월경일을기준으로하였으며최종월경일이불확실한경우에는임신초기에시행한초음파소견을참고로임신주수를산정하였다. 산모의특징으로는나이, 임신전키, 체중및체질량지수, 체외수정 (in vitro fertilization and embryo transfer) 여부, 출산력, 제왕절개술기왕력, 임신중체중증가, 분만시임신주수등을조사하고비교하였다. 산모의임신전체질량지수는체중 / 키 2 (kg/m 2 ) 로구하였고, 우리나라사람과체형이유사하다고판단되는기준인 World Health Organization 아시아-태평양지침 (2000) [8] 에따라저체중 (underweight, <18.5 kg/m 2 ) 군, 정상체중 (normal, 18.5 <23 kg/m 2 ) 군, 과체중 (overweight, 23.0 <25 kg/m 2 ) 군및비만 (obese, 25 kg/ m 2 ) 군의네집단으로분류하였다. 임신중체중증가량은임신전체질량지수에따른 IOM 권고사항을기준으로분류하도록하였다. 다만, IOM에서는전체임신기간동안정상체중군은 kg, 과체중군은 kg, 비만군은 kg의체중증가를권장하는데이는 주의쌍태임신부를기준으로한것이므로단태아보다조산이많이발 생하는쌍태아에그대로적용하기에현실적으로어려움이있다. 따라서본연구에서는 Fox 등 [9] 이이용한방법에의거하여 IOM의권장체중증가량을 37로나눈주당적정체중증가량 ( 정상체중군, kg/ wk; 과체중군, kg/wk; 비만군, kg/wk) 과각산모의주당체중증가량 ( 임신중총체중증가량 / 임신주수 ) 을비교하여권장범위에해당하면 적정군 (normal), 이에못미치면 미달군 (poor), 권장범위를초과하면 초과군 (excessive) 으로분류하였다. 또한 IOM 에는저체중군의권장범위는명시되지않았는데본연구에서는정상체중군의권장범위를함께적용하였다. 임신결과및산모의합병증으로는혈색소수치, 빈혈, 분만방법 ( 제왕절개술또는자연분만 ), 산후출혈, 양수과소증및양수과다증, 조기진통, 자궁경부무력증, 조산, 조기양막파열, 전치태반, 조기태반박리, 유착태반, 임신성고혈압, 임신성당뇨등을조사하고비교하였다. 이중혈색소수치는임신중가장낮았던수치로기록하였으며, 이수치를기준으로 Hg<10 g/dl인경우를빈혈로정의하였고, 산후출혈은제왕절개술시는 1,000 ml 이상의출혈, 자연분만시는 500 ml 이상의출혈이있었던경우로정의하였다. 조기진통은임신 37주이전에자궁수축으로인해수축억제제를투여한경우로하였고조산은재태령 37주미만에분만한경우로하였다. 자궁경부무력증은임신 2삼분기또는 3 삼분기초에통증이나출혈없이자궁경부가개대되는경우로하였으며상기증상없이쌍태임신으로인해예방적으로자궁경부봉축술을시행한경우는제외하였다. 전치태반에는전전치태반, 부분전치태반, 변연전치태반, 하위전치태반을포함하였다. 임신성고혈압은이전에정상혈압이었던산모로임신 20주이후에혈압이 140/90 mm Hg 이상인경우로하였으며, 임신성당뇨는임신 24-28주에시행한 100 g 당부하검사를토대로판정하였다. 신생아합병증으로는 1분및 5분 점수, 5분 점수 7점미만, 신생아집중치료실 (neonatal intensive care unit) 입원, 부당경량아 (small for gestation age), 적정체중아 (appropriate for gestational age), 부당과량아 (large for gestational age) 를조사하고비교하였다. 이중부당경량아는재태기간에비해출생체중이 10백분위수이하인신생아, 부당과량아는 90백분위수이상인신생아로 Lee [10] 가발표한 한국의성별, 태아수별, 출산수별임신주수에따른출생체중 중쌍태아에대한임신주수별체중표와체중곡선을토대로판정하였다. 통계분석은 SPSS ver (SPSS Inc., IBM Company, Somers, NY, USA) 를이용하여카이제곱검정 (χ 2 test), 로지스틱회귀분석 (logistic regression analysis) 을시행하였으며 P<0.05일때통계학적으로유의한것으로판정하였다. 본연구는후향적연구로차의과학대학교임상시험심사위원회 (Institutional Review Board) 의승인을받았다. 임신전체질량지수와임신중체중증가량에따른각군의산모의나 301

3 KJOG Vol. 55, No. 5, 2012 Table 1. Baseline characteristics Weight gain No. (%) Age (yr) (kg/m 2 ) Nulliparity (%) IVF-ET (%) Previous C/Sec (%) Gestational age at delivery (wk) Gestational weight gain (kg) Total Per week Underweight Poor 38 (50.0) 32.8 ± ± ± ± ± 0.06 Normal 35 (46.1) 32.0 ± ± ± ± ± 0.07 Excessive 3 (3.9) 31.7 ± ± ± ± ± 0.10 Normal weight Poor 170 (51.5) 33.3 ± ± ± ± ± 0.07 Normal 135 (40.9) 32.6 ± ± ± ± ± 0.05 Excessive 25 (7.6) 32.6 ± ± ± ± ± 0.08 Overweight Poor 14 (25.5) 34.6 ± ± ± ± ± 0.05 Normal 35 (63.6) 33.6 ± ± ± ± ± 0.06 Excessive 6 (10.9) 32.3 ± ± ± ± ± 0.07 Obese Poor 15 (38.5) 34.2 ± ± ± ± ± 0.37 Normal 15 (38.5) 32.9 ± ± ± ± ± 0.06 Excessive 9 (8.6) 33.0 ± ± ± ± ± 0.05 Total 500 (100) 33.0 ± ± ± ± ± 0.13 Values are presented as number (%) or mean ± standard deviation., body mass index; IOM, Institute of Medicine; IVF-ET, in vitro fertilization and embryo transfer; C/Sec, Cesarean section. Table 2. Frequency of maternal complications Weight gain Anemia Postpartum hemorrhage Preterm labor Preterm birth PROM previa abruption accreta Underweight Poor 16 (42.1) 3 (7.9) 11 (28.9) 15 (39.5) 4 (10.5) 1 (2.6) 0 (0) 1 (2.6) 4 (10.5) 0 (0) Normal 6 (17.1) 1 (2.9) 12 (34.3) 16 (45.7) 10 (28.6) 2 (5.7) 0 (0) 0 (0) 10 (14.3) 0 (0) Excessive 2 (66.7) 0 (0) 0 (0) 1 (33.3) 0 (0) 0 (0) 0 (0) 0 (0) 1 (33.3) 0 (0) Normal weight Poor 1 (24.1) 16 (9.4) 55 (32.4) 85 (50.0) 35 (20.6) 4 (2.4) 1 (0.6) 2 (1.2) 6 (3.5) 10 (5.9) Normal 23 (17.0) 14 (10.4) 34 (25.2) 59 (43.7) 16 (11.9) 4 (3.0) 2 (1.5) 2 (0.7) 15 (11.1) 7 (5.2) Excessive 6 (24.0) 4 (16.0) 8 (32.0) 12 (48.0) 2 (8.0) 2 (8.0) 3 (12.0) 0 (0) 7 (28.0) 1 (4.0) Overweight Poor 4 (28.6) 1 (7.1) 6 (42.9) 8 (57.1) 2 (14.3) 0 (0) 0 (0) 0 (0) 1 (7.1) 0 (0) Normal 11 (31.4) 6 (17.1) 9 (25.7) 13 (37.1) 8 (22.9) 0 (0) 1 (2.9) 1 (2.9) 5 (14.3) 4 (5.7) Excessive 1 (16.7) 1 (16.7) 1 (16.7) 4 (66.7) 1 (16.7) 0 (0) 0 (0) 0 (0) 3 (50.0) 2 (16.7) Obese Poor 4 (26.7) 10 (33.3) 4 (26.7) 8 (53.5) 2 (13.3) 0 (0) 1 (6.7) 2 (13.3) 2 (13.3) 4 (26.7) Normal 3 (20.0) 3 (20.0) 4 (13.3) 7 (46.7) 3 (20.0) 0 (0) 0 (0) 0 (0) 2 (13.3) 3 (20.0) Excessive 0 (0) 2 (22.2) 3 (33.3) 7 (77.8) 1 (11.1) 0 (0) 0 (0) 0 (0) 3 (33.3) 1 (11.1) Total 117 (23.4) 56 (11.2) 145 (29.0) 235 (47.0) 84 (16.8) 13 (2.6) 8 (1.6) 7 (1.4) 54 (10.8) 29 (5.8) Values are presented as number (%)., body mass index; IOM, Institute of Medicine; PROM, premature rupture of membrane; GH, gestational hypertension; GDM, gestational diabetes mellitus. GH GDM 이, nulliparity, 체외수정여부, 분만시임신주수, 임신중총체중증가량및주당체중증가량등전체 12군에따른산모의일반적인특징은 Table 1에나타나있다. 전체연구대상인산모 500명의평균나이는 33.0 ± 3.3세, 평균체질량지수는 21.0 ± 2.8 kg/m 2, 분만시의평균임신주수는 36.1 ± 2.3주였다. 분만방법으로 492명 (98.4%) 이제왕 절개술을, 8명 (1.6%) 이자연분만을시행하였다. 전체 500명의산모를임신전체질량지수를기준으로구분하였을때저체중군 76명 (15.2%), 정상체중군 330명 (66.0%), 과체중군 55명 (11.0%), 비만군 39명 (7.8%) 으로정상체중군이가장많았다. 전체산모를 IOM이권고한체중증가기준에따라구분하였을때에는미달군 302

4 Myung Joo Kim, et al. Pregnancy prognosis in twin pregnancies Table 3. Multivariate logistic regression of maternal complications Weight gain Anemia Underweight Poor 3.68 a ( ) Normal 1.08 ( ) Excessive 7.09 a ( ) Normal weight Poor 1.56 a ( ) Postpartum hemorrhage 0.72 ( ) 0.30 ( ) () 0.96 ( ) PROM ( ) 3.41 a ( ) () 1.80 a ( ) abruption () () () 0.40 ( ) GH 0.93 ( ) 1.59 ( ) 2.40 ( ) 0.26 a ( ) GDM () () () 0.94 ( ) Normal Excessive 1.53 ( ) Overweight Poor 2.09 ( ) Normal 2.45 a ( ) Excessive 0.84 ( ) Obese Poor 1.72 ( ) Normal 1.39 ( ) Excessive () 1.75 ( ) 0.88 ( ) 1.61 ( ) 2.47 ( ) 4.98 a ( ) 2.71 ( ) 2.33 ( ) 0.51 ( ) 0.79 ( ) 2.56 a ( ) 0.97 ( ) 0.95 ( ) 1.59 ( ) 0.80 ( ) 6.19 a ( ) () 2.30 ( ) () 4.69 ( ) () () 3.28 a ( ) 0.59 ( ) ( ) 8.94 a ( ) 1.00 ( ) 1.51 ( ) 3.58 a ( ) 0.86 ( ) () 0.87 ( ) 3.53 ( ) 5.02 a ( ) 4.40 a ( ) 2.38 ( ) Values are presented as odds ratio (95% confi dence interval)., body mass index; IOM, Institute of Medicine; PROM, premature rupture of membrane; GH, gestational hypertension; GDM, gestational diabetes mellitus. a P<0.05. Multivariate logistic regression controlling for age, nulliparity, in vitro fertilization and embryo transfer, gestational age at delivery and previous Cesarean section. In placenta abruption cases, gestational hypertension was added to these controlling factors. 237명 (47.4%), 적정군 220명 (44%), 초과군 43명 (8.6%) 으로나타났다 (Table 1). 임신중총체중증가량은평균 16.3 ± 4.9 kg였고, 이를전체임신주수로나눈주당체중증가량은평균 0.45 ± 0.13 kg/wk였다. 임신전체질량지수및체중증가량에따른 12군별로산모의합병증에대한빈도는 Table 2에나타나있으며, 각종인자의로지스틱회귀분석에의한비교분석결과는 Table 3에나타나있다. 12군간비교시카이제곱검정에서통계학적으로유의한차이가없었던조기진통 ( 총149예, 29.8%), 조산 ( 총235예, 47%), 자궁경부무력증 ( 총6예, 1.2%), 전치태반 ( 총13예, 2.6%), 유착태반 ( 총7예, 1.4%), 양수과소증 ( 총4예, 0.8%) 은다변량로지스틱회귀분석에서제외하였다. 회귀분석시기준집단은체질량지수정상체중군이면서주당체중증가량은적정군으로하였으며, 산모의나이, nulliparity, 체외수정여부, 분만시임신주수, 제왕절개술과거력을보정하여분석하였다. 빈혈은전체산모중 117명 (23.4%) 에서나타났으며, 저체중군중미달군 (odds ratio [OR], 3.68; 95% confidence interval [CI], ) 및초과군 (OR, 7.09; 95% CI, ), 정상체중군중미달군 (OR, 1.56; 95% CI, ), 과체중군중적정군 (OR, 2.45; 95% CI, ) 에서기준집단에비해의미있게빈혈비율이높게나왔다. 산후출혈은비만군중미달군 (OR, 4.98; 95% CI, ) 에서기준집단에비해의미있게높은비율을보였고, 통계학적으로유의하지는않았지만정상체중군, 과체중군, 비만군중초과군 (OR, 1.75; 95% CI, ; OR, 2.47; 95% CI, ; OR, 2.33; 95% CI, ), 비만군중적정군 (OR, 2.71; 95% CI, ) 에서기준집단보다높은비율을보였다. 임신성고혈압은정상체중군, 과체중군, 비만군중초과군 (OR, 3.28; 95% CI, ; OR, 8.94; 95% CI, ; OR, 3.58; 95% CI, ) 에서의미있게비율이증가하였다. 임신성당뇨는비만군중미달군 (OR, 5.02; 95% CI, ) 및적정군 (OR, 4.40; 95% CI, ) 에서의미있게높은발생비율을보였다. 신생아합병증에대한 12군별빈도는 Table 4에나타나있으며, 각합병증에대한발생위험에대해다변량로지스틱회귀분석으로구한것은 Table 5에표시하였다. 회귀분석시산모의나이, nulliparity, 체외수정여부, 분만시임신주수, 제왕절개술과거력을보정하였다. 신생아집중치료실입원은저체중군중미달군 (OR, 2.27; 95% CI, ) 및적정군 (OR, 1.33; 95% CI, ), 정상체중군중미달군 303

5 KJOG Vol. 55, No. 5, 2012 Table 4. Frequency of neonatal complications Weight gain Number (%) Birth weight (g) NICU admission 1 min 5 min 5 < 7 min Underweight Poor 76 (50.0) ± (21.1) 7.5 ± ± (5.3) 8 (10.5) 1 (1.3) Normal 70 (46.1) ± (21.4) 7.3 ± ± (0) 5 (7.1) 5 (7.1) Excessive 6 (3.9) ± (33.3) 6.8 ± ± (33.3) 0 (0) 2 (33.3) Normal weight Poor 340 (51.5) ± (26.2) 7.0 ± ± (7.6) 31 (9.1) 13 (3.8) Normal 270 (40.9) ± (17.0) 7.2 ± ± (4.1) 11 (4.1) 20 (7.4) Excessive 50 (7.6) ± (32.0) 6.9 ± ± (14.0) 3 (6.0) 8 (16.0) Overweight Poor 28 (25.5) ± (32.1) 6.8 ± ± (17.9) 1 (3.6) 0 (0) Normal 70 (63.6) ± (18.6) 7.4 ± ± (5.7) 5 (7.1) 5 (7.1) Excessive 12 (10.9) ± (66.7) 6.5 ± ± (0) 1 (8.3) 2 (16.7) Obese Poor 30 (38.5) ± (23.3) 7.0 ± ± (10.0) 0 (0) 4 (13.3) Normal 30 (38.5) ± (16.7) 7.0 ± ± (6.7) 2 (6.7) 3 (10.0) Excessive 18 (8.6) ± (27.8) 6.8 ± ± (22.2) 0 (0) 4 (22.2) Total 1,000 (100) ± (23.1) 7.1 ± ± (6.8) 67 (6.7) 67 (6.7) Values are presented as number (%) or mean ± standard deviation., body mass index; IOM, Institute of Medicine; NICU, neonatal intensive care unit; SGA, small for gestational age; LGA, large for gestational age. Table 5. Multivariate logistic regression of neonatal complications Weight gain NICU admission 5 < 7 min Underweight Poor 2.27 ( ) 1.49 ( ) 2.44 ( ) 0.17 ( ) Normal 1.33 ( ) () 1.74 ( ) 0.78 ( ) Excessive 0.11 ( ) 6.91 ( ) () 7.86 a ( ) Normal weight Poor 1.29 ( ) 1.54 ( ) 2.21 a ( ) 0.48 ( ) Normal Excessive 1.19 ( ) 3.89 a ( ) 1.84 ( ) 2.75 a ( ) Overweight Poor 0.67 ( ) 2.57 ( ) 0.84 ( ) () Normal 1.14 ( ) 2.95 ( ) 1.65 ( ) 0.99 ( ) Excessive a ( ) () 2.70 ( ) 2.71 ( ) Obese Poor 1.25 ( ) 1.85 ( ) () 1.55 ( ) Normal 0.34 ( ) 0.73 ( ) 1.83 ( ) 1.36 ( ) Excessive 0.87 ( ) a ( ) () 4.40 a ( ) Values are presented as odds ratio (95% confi dence interval)., body mass index; IOM, Institute of Medicine; NICU, neonatal intensive care unit; SGA, small for gestational age; LGA, large for gestational age. a P<0.05. Multivariate logistic regression controlling for age, nulliparity, in vitro fertilization and embryo transfer, gestational age at delivery and previous Cesarean section. SGA SGA LGA LGA (OR, 1.29; 95% CI, ) 이기준군보다높은발생비율을보였으나통계학적으로유의하지는않았고, 과체중군중초과군 (OR, 11.21; 95% CI, ) 에서기준군보다의미있게높은발생비율을보였다. 5분 점수 7점미만은정상체중군및비만군중초과군 (OR, 3.89; 95% CI, ; OR,11.72; 95% CI, ) 에서발생비율이유의하게높게나타났다. 부당경량아는정상체중군중미 달군 (OR, 2.21; 95% CI, ) 에서기준군보다유의하게높은발생비율을보였으며, 부당과량아는저체중군, 정상체중군, 비만군중초과군에서 (OR, 7.86; 95% CI, ; OR, 2.75; 95% CI, ; OR, 4.40; 95% CI, ) 높은발생비율로나타났다. 전체 500명의쌍태산모를다시임신중주당체중증가량에따른 3 304

6 Myung Joo Kim, et al. Pregnancy prognosis in twin pregnancies Table 6. Multivariate logistic regression of maternal and neonatal complications Weight gain Poor Anemia 1.51 a ( ) Preterm birth 1.09 ( 5.98) abruption 0.63 ( ) GH 0.37 a ( ) NICU admission 1.31 ( ) 5 min < ( ) SGA 1.52 ( ) LGA 0.49 a ( ) Normal Excessive 1.03 ( ) 0.52 ( 6.00) 3.12 ( ) 3.27 a ( ) 1.66 ( ) 3.43 a ( ) 1.22 ( ) 3.05 a ( ) Values are presented as odds ratio (95% confi dence interval). IOM, Institute of Medicine; GH, gestational hypertension; NICU, neonatal intensive care unit; SGA, small for gestational age; LGA, large for gestational age. a P<0.05. Multivariate logistic regression controlling for age, nulliparity, in vitro fertilization and embryo transfer, gestational age at delivery, previous Cesarean section and prepregnancy. In placenta abruption cases, gestational hypertension was added to these controlling factors. Table 7. Multivariate logistic regression of maternal complications Anemia Postpartum hemorrhage accreta GH GDM Underweight 1.76 a ( ) 0.49 ( ) 1.32 ( ) 2.01 a ( ) () Normal weight Overweight 1.65 a ( ) 1.46 ( ) 1.74 ( ) 2.13 a ( ) 0.86 ( ) Obese 0.32 ( ) 3.30 a ( ) 3.54 ( ) 3.27 a ( ) 4.49 a ( ) Values are presented as odds ratio (95% confi dence interval)., body mass index; GH, gestational hypertension; GDM, gestational diabetes mellitus. a P<0.05. Multivariate logistic regression controlling for age, nulliparity, in vitro fertilization and embryo transfer, gestational age at delivery, previous Cesarean section and gestational weight gain per week. 군및임신전체질량지수에따른 4군별로각각나누어추가적으로임신예후에대한로지스틱회귀분석을시행한결과는 Tables 6과 7에나타나있다. 3군간또는 4군간비교시카이제곱검정에서통계학적으로유의한차이가있었던인자들을대상으로다변량로지스틱회귀분석을시행하였고기준집단은임신전체질량지수정상체중군 (Table 6) 또는임신중주당체중증가량적정군 (Table 7) 으로하였다. 회귀분석시산모의나이, nulliparity, 체외수정여부, 분만시임신주수, 제왕절개술과거력을보정하였으며임신전체질량지수및임신중주당체중증가량또한상호보정하였다. 임신중체중증가량에따른 3군비교 (Table 6) 시빈혈은미달군 (OR, 1.51; 95% CI, ) 에서유의하게높은발생비율로나타났고, 임신성고혈압은미달군 (OR, 0.37; 95% CI, ) 에서낮은발생비율을보인반면초과군 (OR, 3.27; 95% CI, ) 에서는높은발생비율을보였다. 신생아합병증으로는 5분 점수 7점미만이초과군에서유의하게높게발생하였고 (OR, 3.43; 95% CI, ), 부당과량아는미달군 (OR, 0.49; 95% CI, ) 에서낮은발생비율, 초과군 (OR, 3.05; 95% CI, ) 에서높은발생비율을보였다. 임신전체질량지수에따른 4군비교 (Table 7) 시빈혈은저체중군 (OR, 1.76; 95% CI, ) 및과체중군 (OR, 1.65; 95% CI, ) 에서발생비율이높았다. 산후출혈과임신성당뇨는비만군 (OR, 3.30; 95% CI, ; OR, 4.49; 95% CI, ) 에서높은발생비율을보였다. 임신성고혈압은정상체중군을제외한모든군 ( 저 체중군 OR, 2.01; 95% CI, ; 과체중군 OR, 2.13; 95% CI, ; 비만군 OR, 3.27, 95% CI, ) 에서발생비율이높게나타났다. 신생아합병증에관련된인자들 ( 신생아집중치료실입원, 5분 점수 7점미만, 부당경량아, 부당과량아 ) 은임신전체질량지수 4군으로카이제곱검정시통계학적으로유의한인자는없었고따라서다변량로지스틱회귀분석에서도제외되었다. 쌍태임신은단태임신에비해임신예후가불량한것으로알려져있다. 일반적으로빈혈은단태임신에서 1%-4% 로알려져있는데쌍태임신에서는 11.1%-41.8% 로보고된바있다 [11-13]. 단태임신에서조산의발생비율은국가별로 4%-12.3% [14,15], 국내 년동안의전국적인평균조산율은 7.3% [16] 로보고되었으며, 임신성고혈압은 5%, 임신성당뇨는 1.5%-4.5%, 부당경량아 5.8%-11.1%, 부당과중아 5.5%-12.3%, 신생아집중치료실입원은 6%-8.2% 로알려져있다 [17-21]. 이에비해쌍태임신에서는임신전정상체질량지수이면서임신중체중증가가정상인경우 37주미만의조산발생비율은 57.9%, 35주미만의조산은 19.8%, 임신성고혈압 8.2%-8.7%, 임신성당뇨 4.1%-4.8%, 부당경량아 18.8%, 부당과중아 3.9%, 신생아집중치료실입원은 10.2% 로보고되었다 [9,22,23]. 이는단태임신에비해 305

7 KJOG Vol. 55, No. 5, 2012 쌍태임신전반에서임신예후가불량할뿐아니라쌍태임신내의하위그룹인임신전정상체질량지수및임신중정상체중증가를가진산모군의임신예후역시단태임신보다더불량함을시사한다. 본연구를통해서는쌍태임신에대해산모의체중요소로각하위그룹을비교분석해보았을때임신전체질량지수및임신중체중증가에따라특정임신예후 ( 빈혈, 임신성고혈압, 임신성당뇨, 5분 점수, 부당경량아, 부당과량아등의위험도 ) 에독립적으로연관성이있음을확인할수있었다. 빈혈은단태임신보다쌍태임신에서혈장량이더많이증가하여생리적빈혈이초래되고철분과엽산염의요구가더높아져쌍태임신산모에서보다빈번하게발생하는것으로알려져있다 [24]. 본연구에서는전체 500명산모중 117명 (23.4%) 에서빈혈이있었는데이는 Robertson과 Neer [25] 가발표한 40%, 국내 Park 등 [12] 의 41.6%, Lee 등 [13] 의 41.8% 보다는적은수치이지만, 15,484명의다태임신산모를대상으로한 Conde-Agudelo 등 [11] 의 11.1% 보다는많은수치이다. 과거의국내연구자들보다더적게나타났던것은모성빈혈에는임신중철분요구량증가뿐아니라사회경제적여건역시영향을미치는데 [26], 임신부들이과거에비해병원에접근성도더좋아지고산전관리에대한관심도더높아졌으며철분제도더주의해서복용하기때문일것으로사료된다. 임신성고혈압은 12군비교시정상체중군, 과체중군, 비만군의초과군에서기준군보다발생률이유의하게높게나타났고임신중체중증가량에따른 3군비교시미달군에서는발생률이낮았고초과군에서는발생률이높았다. 임신성당뇨는 12군비교시비만군중미달군, 적정군에서통계학적으로유의하게발생률이높으며임신전체질량지수에따른 4군비교시비만군에서높게나타났다. 따라서본연구에서는임신성고혈압은임신전체질량지수보다는임신중체중증가가, 임신성당뇨는임신중체중증가보다는임신전체질량지수가더영향을미치는것으로해석된다. 신생아의주산기예후중신생아집중치료실입원은 Lee 등 [22] 의연구에서는 12군별로통계학적으로유의한발생률의차이가없었으나본연구에서는과체중군중초과군에서기준군보다발생률이높게나타났다. 하지만본연구에서전체 1,000명의신생아중단 12명만으로구성된이그룹은다른군보다표본수가현저히적고임신전체질량지수 4군또는임신중체중증가량 3군별로시행한회귀분석에서는통계적으로유의하게연관된그룹이없었으므로이에대해서는추가적인조사가필요할것으로판단된다. 신생아예후중 5분 점수 7점미만은 12군비교시정상체중군및비만군중초과군에서, 임신중체중증가량에따른 3군비교시에도초과군에서높게발생하는것으로나타났다. 부당경량아는 12군비교시정상체중군중미달군이통계학적으로유의하게발생률이높게나타났고, 유의하진않지만저체중군중미달군에서도발생률이높았다. 부당과량아발생비율은 12군비교시저체중군, 정상체중군, 비만군중초과군에서높게, 임신중체중증가량에따른 3군비교시미달군에서는낮게, 초과군에서는높게나타났다. 종합해보면, 5분 점수, 부당경량아, 부당과량아의발생위험에는산모의임신전체질량지수보다는임신중체중증가정도가더영향을미치는것으로파악된다. 결과적으로임신전체질량지수를기준으로저체중군산모는빈혈의발생비율이높고, 비만군산모에서는임신성당뇨의발생비율이높은한편, 임신중체중증가가초과된경우에는임신성고혈압발생이높아지며 5분 점수 7점미만, 부당과량아의발생비율이높고체중증가가미달인경우에는빈혈의발생비율이높아지는양상으로볼때, 임신전정상적인체질량지수및임신중적절한체중증가가이루어지지않으면불량한임신예후가따르는것을알수있다. Nehring 등 [27] 은임신중체중증가와산후체중저류에대한메타분석에서 1990년 IOM 권고안보다임신중체중증가량이많았던산모에서는산후체중저류가분만후 3년째평균 3.06 kg, 분만후 15년이상경과했을때에는평균 4.72 kg이었다고보고하였다. 또한 Fisch 등 [28] 은임신전심하게마르거나비만한산모혹은임신중과소또는과도한체중증가를보인산모는출생아의체중뿐만아니라이들출생아의 4세및 7세때의체중에도영향을미친다고하였다. 따라서장기적인관점에서도단태임신뿐아니라쌍태임신에서도산모및신생아의예후를향상시키기위해영양, 생활습관, 운동에걸쳐적절한상담을통해임신전에체질량지수를정상화하고임신중에적절한체중증가를가져오도록하는노력이필요하겠다. 본연구의장점은첫째, 최근 3년간분만한 500명의쌍태임신산모를대상으로산모및태아의체중과관련된여러가지인자들을분석하고임신결과에대해전반적으로살펴보았다는것이다. 둘째로, 2009 년새로개정된 IOM 권고사항을기초로연구했으며, 쌍태임신에관한선행국내연구에서는 34주이상만을다루었으나본연구에서는 IOM 권고사항을응용하면서그범위를확대해해당기간본원에서분만시생존했던모든쌍태임신을연구에포함해그대상이폭넓다는것이다. 셋째, 연구결과에영향을줄수있는산모의나이, 산과력, 체외수정여부, 제왕절개술기왕력, 분만시임신주수등을통계학적으로보정하였다는점이다. 본연구의한계점으로는첫째, 후향적연구라는점이다. 두번째로는본연구의자료인전자의무기록시스템 (electronic medical record) 상기입된산모의체중은외래내원시마다는실제측정치이지만임신전키와체중은산모의기억에의존하므로정확히기록되지않았을수있다는점이다. 셋째, 산모의체중에영향을미치는인자중흡연력, 음주및불법약물복용여부, 사회경제적상태, 식습관, 육체적및직업적활동도, 스트레스등을분석에넣지못하였다. 넷째, IOM에서제시한권장체중증가범위를수용하면서체질량지수는 WHO 아시아-태평양기준으로적용하였기에여기에따르는 bias가있을수있다. 현재 IOM의기준은미국인을대상으로한것으로인종에대해서는따로고려해권장범위를제시하고있지않다. 또한 IOM은단태임신에있어서는임신삼분기별권장범위를추가로제시하고있지만, 쌍태임신에대해서는임신중총체중증가량에대한기준자체도 provisional 이라는단서가있으며임신삼분기별권장범위는없는실정이다. 306

8 Myung Joo Kim, et al. Pregnancy prognosis in twin pregnancies 앞으로한국인산모에게보다적절한체질량지수및체중증가권장범위에대한기준이연구되어제시되어야할것이다. 또한본연구는후향적연구로앞으로쌍태임신에서산모의체질량지수및체중증가에따른임신예후에대해대규모의전향적연구가필요할것으로사료된다. References 1. Castro LC, Avina RL. Maternal obesity and pregnancy outcomes. Curr Opin Obstet Gynecol 2002;14: Nohr EA, Vaeth M, Baker JL, Sørensen TIa, Olsen J, Rasmussen KM. Combined associations of prepregnancy body mass index and gestational weight gain with the outcome of pregnancy. Am J Clin Nutr 2008;87: Thorsdottir I, Torfadottir JE, Birgisdottir BE, Geirsson RT. Weight gain in women of normal weight before pregnancy: complications in pregnancy or delivery and birth outcome. Obstet Gynecol 2002;99: Kabiru W, Raynor BD. Obstetric outcomes associated with increase in category during pregnancy. Am J Obstet Gynecol 2004;191: Luke B. Reducing fetal deaths in multiple births: optimal birthweights and gestational ages for infants of twin and triplet births. Acta Genet Med Gemellol (Roma) 1996;45: Rasmussen KM, Yaktine AL; Institute of Medicine; National Research Council; Committee to Reexamine IOM Pregnancy Weight Guidelines. Weight gain during pregnancy: reexamining the guidelines. Washington, DC: National Academies Press (US); Korean Statistical Information Service [Internet]. Daejeon: Statistics Korea; c2010 [cited 2012 Apr 15]. Availavle from: kr/ups/ups_01list01.jsp?grp_no=1002&pubcode=cc&type=f. 8. WHO Western Pacific Region. International Association for the Study of Obesity. International Obesity Task Force. The Asia-Pacifi c perspective: redefi ning obesity and its treatment [Internet]. Sydney: Health Communications Austrailia; 2000 [cited 2012 April 27]. Available from: doc/ /obesity-guidelines-for-asia-pecifi c. 9. Fox NS, Rebarber A, Roman AS, Klauser CK, Peress D, Saltzman DH. Weight gain in twin pregnancies and adverse outcomes: examining the 2009 Institute of Medicine guidelines. Obstet Gynecol 2010;116: Lee JJ. Birth weight for gestational age patterns by sex, plurality, and parity in Korean population. Korean J Pediatr 2007;50: Conde-Agudelo A, Belizán JM, Lindmark G. Maternal morbidity and mortality associated with multiple gestations. Obstet Gynecol 2000;95: Park YC, Ko SH, Lee TI, Ma JN, Jung KW, Weon JC, et al. Clinical analysis of 149 cases of twin pregnancies. Korean J Obstet Gynecol 2000;43: Lee GR, Park KH, Park JS, Lee WM, Cha JY, Kim HH, et al. Statistical analysis of twin pregnancy for 10 tears (1993~2002). Korean J Obstet Gynecol 2003;46: Mamun AA, Callaway LK, O Callaghan MJ, Williams GM, Najman JM, Alati R, et al. Associations of maternal pre-pregnancy obesity and excess pregnancy weight gains with adverse pregnancy outcomes and length of hospital stay. BMC Pregnancy Childbirth 2011;11: Kang MC, Cho HJ, Choi SJ, Han SJ, Song CH. Epidemiologic study of preterm birth in Chosun University Hospital. Korean J Obstet Gynecol 2004;47: Koo YH, Kim SK, Shim JY, Won HS, Lee PR, Kim A. Analysis of preterm birth tate based on birth certifi cate data: from 1995 to Korean J Obstet Gynecol 2006;49: Hauth JC, Ewell MG, Levine RJ, Esterlitz JR, Sibai B, Curet LB, et al. Pregnancy outcomes in healthy nulliparas who developed hypertension. Calcium for Preeclampsia Prevention Study Group. Obstet Gynecol 2000;95: Tsukamoto H, Fukuoka H, Inoue K, Koyasu M, Nagai Y, Takimoto H. Restricting weight gain during pregnancy in Japan: a controversial factor in reducing perinatal complications. Eur J Obstet Gynecol Reprod Biol 2007;133: Kang CH, Kim MR, Choi MY, Kang EJ, Kim HJ, Seo SS. Clinical comparison of maternal characteristics and pregnancy outcomes between gestational diabetes and general obstetric population. Korean J Obstet Gynecol 2001;44: Park HJ, Lee SH, Cha DH, Kim IH, Jun HS, Lee KJ, et al. Pregnancy outcomes in women aged 35 and older. Korean J Obstet Gynecol 2006;49: Wisborg K, Ingerslev HJ, Henriksen TB. In vitro fertilization and preterm delivery, low birth weight, and admission to the neonatal intensive care unit: a prospective follow-up study. Fertil Steril 2010;94: Lee EJ, Kim YH, Kwon JY, Park YW. Pregnancy outcome according to gestational weight gain in twin pregnancies on the basis of the 2009 Institute of Medicine recommendations. Korean J Obstet Gynecol 2010;53: Fox NS, Saltzman DH, Kurtz H, Rebarber A. Excessive weight gain in term twin pregnancies: examining the 2009 Institute 307

9 KJOG Vol. 55, No. 5, 2012 of Medicine defi nitions. Obstet Gynecol 2011;118: Pritchard JA. Changes in the Blood Volume during Pregnancy and Delivery. Anesthesiology 1965;26: Robertson EG, Neer KJ. l injection studies in twin gestation. Am J Obstet Gynecol 1983;147: Kim HJ, Kim WS, Lee CH, Rha DJ, Lee JK, Kim SP. Statistical analaysis of twin pregnancy for 10 years ( ). Korean J Obstet Gynecol 1988;31: Nehring I, Schmoll S, Beyerlein A, Hauner H, von Kries R. Gestational weight gain and long-term postpartum weight retention: a meta-analysis. Am J Clin Nutr 2011;94: Fisch RO, Bilek MK, Ulstrom R. Obesity and leanness at birth and their relationship to body habitus in later childhood. Pediatrics 1975;56: 쌍태임신에서임신전체질량지수및임신중체중증가에따른임신예후 차의과학대학교의과대학 1 산부인과학교실, 2 내과학교실김명주 1, 나은덕 1, 이경진 1, 차동현 1, 신중식 1, 이화영 2 목적 2009년개정된 Institute of Medicine 의권고안에근거하여쌍태임신산모의임신전체질량지수 (body mass index, ) 및임신중체중증가량에따른임신예후를분석하고자한다. 연구방법 2008년 1월부터 2010년 12월까지분만한쌍태임신산모 500명및쌍태아 1,000명을대상으로후향적으로연구하였다. 산모의임신전 에따라저체중 (<18.5 kg/m 2 ) 군, 정상체중 (18.5 I<23 kg/m 2 ) 군, 과체중 (23.0 I<25 kg/m 2 ) 군, 비만 ( 25 kg/m 2 ) 군, IOM의임신중권장체중증가량에따라미달군, 적정군, 초과군으로나누어비교분석하였다. 결과전체 500명산모중저체중군 76명 (15.2%), 정상체중군 330명 (66.0%), 과체중군 55명 (11.0%), 비만군 39명 (7.8%), 미달군 237명 (47.4%), 적정군 220명 (44%), 초과군 43명 (8.6%) 이었다. 임신중총체중증가량은평균 16.3±4.9 kg, 주당체중증가량은평균 0.45±0.13 kg/wk 였다. 저체중군및미달군에서빈혈, 비만군에서는임신성당뇨의발생비율이높았다. 초과군에서는부당과량아, 임신성고혈압, 신생아의 5분 점수 7점미만의발생률이높게나타났다. 결론쌍태임신에서임신전저체중또는비만인경우, 임신중체중증가가적거나과도한경우에불량한임신예후와연관이높다. 따라서상담및교육을통해임신전정상체질량지수를유지하고임신중적절한체중증가를이끄는것이중요하다. 중심단어 : 쌍태임신, 체질량지수, 임신중체중증가, 임신예후 308