日本新生児成育医学会雑誌　第29巻　第2号　87～93頁（2017年）

日本新生児成育医学会雑誌　29(2)：361-367；2017　

受付日：平成28．03．22

受理日：平成29．01．10

当院における極低出生体重児における身体発育の検討
―第二報：zスコアを用いた子宮外発育障害の評価と周産期因子の及ぼす影響について―

New Index, Δz, may be a Useful Marker to Evaluate Extra-Uterine Growth in Very Low Birth Weight Infants

国立病院機構佐賀病院　総合周産期母子医療センター　小児科

Department of Pediatrics, National Hospital Organization, Saga National Hospital

江頭智子・七條了宣・江頭政和・水上朋子・高柳俊光

Tomoko EGASHIRA，Akinori SHICHIJYO，Masakazu EGASHIRA，Tomoko MIZUKAMI，Toshimitsu TAKAYANAGI

Key Words：z score，very low birth weight infant，extrauterine growth restriction，nutrition，factor in perinatal

　FGR（子宮内発育制限）の程度にかかわらず，極低出生体重児の出生から受胎後40週にかけての身体発育を子宮内発育と比較する指標としてΔzを提唱し，NICU入院中の身体発育を評価した。対象は在胎30週以下の出生体重10％ tile 以上の極低出生体重児274名（出生体重1,032±287g，在胎週数27.4±2.3週）。Δzは「予定日体重（頭囲）zスコア－出生時体重（頭囲）zスコア」で算出し，Δz≧0 を良好群，Δz＜0を不良群と定義した（図1）。またΔz≧0に寄与する周産期因子の抽出を試みた。その結果，体重Δz≧0は274例中44名（16％），頭囲Δz≧0は274例中200名（73％）に認められた。体重Δz≧0に有意に寄与する周産期因子として「在胎週数」，「より小さな出生体重zスコア」と「より多い受胎後35週経腸栄養量」が，頭囲Δz≧0に有意に寄与する因子として「より短い人工換気日数」と「より小さな出生頭囲zスコア」が選択された。出生時zスコアと予定日zスコア，Δzの3指標を用いることで，FGRとEUGR，生後のキャッチアップの程度を客観的に評価できる可能性がある。

　In order to evaluate the degree of extra-uterine growth in very low birth weight infants（ VLBWI） irrespective of the degree of fetal growth restriction, we proposed a new concept referred to as Δz, which uses a calculation by deducting the SD score at birth from the SD score 40 weeks after gestation. We assessed extra-uterine growth as being good when Δz was ≧0 and assessed growth as poor when Δz was ＜0. The study subjects included 274 VLBWI whose birth weights were greater than the 10th percentile for their gestational age, whose gestational age and birth weight were 27.4±2.3 wks and 1,032±287 grams, respectively, and for which the Δz of body weight（ BW） and head circumference（ HC） had been evaluated for each subject. The results showed that the Δz of BW was determined as being good in 44（ 16％） infants, and Δz of HC was determined as being good in 200（ 73％） infants. A multiple regression analysis revealed that gestational age at birth, a lower SD score of BW at birth, and a larger amount of feeding volume at 35 wks after gestation should have significant effects on Δz ≧0 in body weight, and a shorter duration of intra-tracheal ventilation therapy and a lower SD score of HC at birth also have significant effects on Δz ≧0 in head circumference. The degree of catch up of growth from birth can be objectively evaluated with the z score at birth, the z score at term, and Δz.