Table 4.

Evaluation of effect heterogeneity among selected maternal and birth characteristics and childhood rhabdomyosarcoma histologic subtypes

Characteristic	Embryonal RMS n=215		Alveolar RMS n=66
	ORa	95% CI	ORa	95% CI	p for heterogeneity
Ever used any birth control	1.19	0.80–1.79	1.41	0.75–2.62	0.624
Using birth control when became pregnant	1.51	0.59–3.90	1.13	0.23–5.40	0.706
Spotting/cramping/abnormal vaginal bleeding	1.80	1.10–2.92	2.49	1.25–5.00	0.357
Anemia during pregnancy	1.17	0.72–1.88	1.26	0.61–2.62	0.842
Type of delivery
Vaginal	1.00	Reference	1.00	Reference
Cesarean	1.60	1.00–2.56	1.18	0.53–2.63	0.449
Birth weightb
Normal (2,500g to <4,000g)	1.00	Reference	1.00	Reference
LBW (<2,500g)	1.64	0.62–4.32	4.46	1.41–14.1
HBW (≥4,000g)	1.61	0.93–2.79	2.41	1.09–5.35	0.169
Length of pregnancyc
Normal	1.00	Reference	1.00	Reference
Premature	2.47	0.93–6.59	0.95	0.23–4.00
Overdue	0.58	0.33–1.02	0.95	0.44–2.08	0.155

RMS = rhabdomyosarcoma; OR = odds ratio; CI = confidence interval; LBW = low birth weight; HBW = high birth weight

^aAdjusted for sex, age, and race.

^bAdjusted for length of pregnancy.

^cAdjusted for birth weight.