Table 2 Hazard ratio of gestational headache in each of the four outcomes considering interaction with history of headache disorder

Gestational headache

1.39 (1.11–1.75)

1.19 (0.84–1.69)

1.49 (1.10–2.02)

1.63 (1.17–2.28)

1.12 (0.57–2.20)

History of headache

1.61 (1.21–2.14)

1.83 (1.26–2.67)

1.53 (1.03–2.28)

1.99 (1.33–2.96)

1.35 (0.59–3.06)

Interaction term (G-HA x Hx-HA)

1.65 (0.97–2.83)

2.11 (1.04–4.32)

1.38 (0.64–2.98)

0.68 (0.26–1.75)

4.29 (1.15–16.03)