Table 2. Prospective risks of stillbirth and neonatal death for 2 consecutive weeks at term, and the number needed to harm (NNH) for 1 additional stillbirth when pregnancy is continued to the next week.

Gestational age (weeks)	Number of studies	Number of stillbirths	Number of pregnancies	Risk ratio*	95% CI**	Risk difference* (×1,000)	95% CI**	NNH***	95% CI**
Stillbirth
37+0–6	12	3,250	8,566,961	1.29	1.18, 1.40	0.11	0.07, 0.15	9,058	6,714, 13,724
38+0–6	12	3,516	8,032,865	1.32	1.22, 1.44	0.16	0.11, 0.21	6,242	4,735, 8,839
39+0–6	12	3,620	6,784,040	1.64	1.51, 1.79	0.42	0.35, 0.50	2,367	1,997, 2,852
40+0–6	12	3,426	4,687,330	1.64	1.51, 1.77	0.69	0.57, 0.81	1,449	1,237, 1,747
41+0–6	12	2,407	2,273,471	1.94	1.72, 2.19	1.66	1.29, 2.06	604	486, 775
42+0–6	12	1,335	700,610	1.93	1.50, 2.36	3.18	1.84, 4.35	315	230, 543
≥43	6	276	82,039	—	—	—	—	—	—
Neonatal death
37+0–6	5	296	552,964	0.41	0.26, 0.57	−0.52	−0.76, −0.31	−1,923	−3,226, −1,316
38+0–6	5	428	1,210,730	0.94	0.68, 1.49	−0.02	−0.14, 0.12	−50,000	−7,143, 8,333
39+0–6	5	560	2,029,277	1.13	0.90, 1.50	0.05	−0.04, 0.14	20,000	−25,000, 7,143
40+0–6	5	669	2,197,643	0.85	0.64, 1.13	−0.06	−0.15, 0.04	−16,667	−6,667, 25,000
41+0–6	5	347	1,127,117	1.87	1.07, 2.86	0.28	0.02, 0.54	3,571	1,852, 50,000
42+0–6	4	44	70,322	1.32	0.20, 3.38	0.19	−0.52, 1.22	5,263	−1,923, 820
≥43	4	4	6,370	—	—	—	—	—	—

*Risk differences and risk ratios refer to the change in the risk of delivering 1 week later as compared to delivering at that age.

**Bootstrap CI 95% (P_2.5th, P_97.5th).

***Number needed to harm when pregnancy is prolonged to the next week, compared to delivery at that gestation, to experience 1 additional stillbirth or neonatal death.