Department of Public Health and Primary Health Care, University of Bergen, PO Box 7804, N-5020 Bergen, Norway.
JAMA. 2010 Sep 1;304(9):976-82. doi: 10.1001/jama.2010.1271.
Although preterm delivery is a well-established risk factor for cerebral palsy (CP), preterm deliveries contribute only a minority of affected infants. There is little information on the relation of CP risk to gestational age in the term range, where most CP occurs.
To determine whether timing of birth in the term and postterm period is associated with risk of CP.
DESIGN, SETTING, AND PARTICIPANTS: Population-based follow-up study using the Medical Birth Registry of Norway to identify 1,682,441 singleton children born in the years 1967-2001 with a gestational age of 37 through 44 weeks and no congenital anomalies. The cohort was followed up through 2005 by linkage to other national registries.
Absolute and relative risk of CP for children surviving to at least 4 years of age.
Of the cohort of term and postterm children, 1938 were registered with CP in the National Insurance Scheme. Infants born at 40 weeks had the lowest risk of CP, with a prevalence of 0.99/1000 (95% confidence interval [CI], 0.90-1.08). Risk for CP was higher with earlier or later delivery, with a prevalence at 37 weeks of 1.91/1000 (95% CI, 1.58-2.25) and a relative risk (RR) of 1.9 (95% CI, 1.6-2.4), a prevalence at 38 weeks of 1.25/1000 (95% CI, 1.07-1.42) and an RR of 1.3 (95% CI, 1.1-1.6), a prevalence at 42 weeks of 1.36/1000 (95% CI, 1.19-1.53) and an RR of 1.4 (95% CI, 1.2-1.6), and a prevalence after 42 weeks of 1.44 (95% CI, 1.15-1.72) and an RR of 1.4 (95% CI, 1.1-1.8). These associations were even stronger in a subset with gestational age based on ultrasound measurements: at 37 weeks the prevalence was 1.17/1000 (95% CI, 0.30-2.04) and the relative risk was 3.7 (95% CI, 1.5-9.1). At 42 weeks the prevalence was 0.85/1000 (95% CI, 0.33-1.38) and the relative risk was 2.4 (95% CI, 1.1-5.3). Adjustment for infant sex, maternal age, and various socioeconomic measures had little effect.
Compared with delivery at 40 weeks' gestation, delivery at 37 or 38 weeks or at 42 weeks or later was associated with an increased risk of CP.
尽管早产是脑瘫（CP）的一个既定危险因素，但早产只导致少数受影响的婴儿。在大多数 CP 发生的足月范围内，关于 CP 风险与胎龄的关系的信息很少。
确定在足月和过期期间出生的时间是否与 CP 风险相关。
设计、地点和参与者：使用挪威医学出生登记处进行基于人群的随访研究，以确定 1682441 名胎龄为 37 至 44 周且无先天畸形的单胎儿童。该队列通过与其他国家登记处的链接，在 2005 年之前进行了随访。
至少 4 岁时 CP 的绝对和相对风险。
在足月和过期儿童的队列中，1938 名儿童在国家保险计划中登记患有 CP。40 周出生的婴儿 CP 风险最低，患病率为 0.99/1000（95%置信区间[CI]，0.90-1.08）。分娩越早或越晚，CP 的风险越高，37 周的患病率为 1.91/1000（95%CI，1.58-2.25）和相对风险（RR）为 1.9（95%CI，1.6-2.4），38 周的患病率为 1.25/1000（95%CI，1.07-1.42）和 RR 为 1.3（95%CI，1.1-1.6），42 周的患病率为 1.36/1000（95%CI，1.19-1.53）和 RR 为 1.4（95%CI，1.2-1.6），42 周后患病率为 1.44（95%CI，1.15-1.72）和 RR 为 1.4（95%CI，1.1-1.8）。在基于超声测量的胎龄的子集中，这些关联甚至更强：37 周时的患病率为 1.17/1000（95%CI，0.30-2.04），相对风险为 3.7（95%CI，1.5-9.1）。42 周时的患病率为 0.85/1000（95%CI，0.33-1.38），相对风险为 2.4（95%CI，1.1-5.3）。调整婴儿性别、母亲年龄和各种社会经济措施几乎没有影响。
与 40 周妊娠相比，37 周或 38 周或 42 周或更晚分娩与 CP 风险增加相关。
