Characteristics of included studies focusing on the haemorrhage of brain arteriovenous malformation during pregnancy and puerperium
| Study | Country | Ethnicity | Medical centre (study period) | Study design | Included patients, n | Definition of risk period | Definition of control period | Risk period | Control period | Statistical analysis | RR (95% CI) | |||||
| Pregnancy | Abortion | Event | Person-years | Incidence density (person-years) | Event | Person-years | Incidence density (person-years) | |||||||||
| Horton et al11 | USA | NA | Massachusetts General Hospital (1977–1986) | CCOS | Female bAVMs receiving proton beam therapy (n=451)* | 40-week gestation and 12-week postpartum | 0.3 years (according to the average 12-week abortion and 6-week postabortion period) | Age at treatment subtracting both risk priod and 15 years | 17 | 469 | 0.035±0.005 (0.024–0.045) | 442 | 13 766 | 0.031±0.002 (0.028–0.034) | NA | NA |
| Forster et al15 | UK | NA | Leksell Gamma Unit (1985–1991) | CCOS | Female bAVMs from 15 to 45 years receiving treatment of SRS (n=191)* | 40-week gestation | NA | Age at SRS subtracting both risk priod and 15 years | 15 | 187 | 0.093 | 207 | 3402 | 0.045 | NA | NA |
| Fujita et al16 | Japan | NA | University of Tsukuba (1978–1995) | CCOS | Female bAVMs (n=42)* | 40-week gestation and 12-week postpartum | NA | Age at treatment subtracting risk priod (21–38 years) | 3 | 46 | 0.065±0.036 (0.020–0.180) | 5 | 341 | 0.015±0.007 (0.004–0.031) | NA | NA |
| Bradley and Rose10 | USA | NA | Brigham and Women’s Hospital (2002–2010) | CCOS | Female bAVMs (n=58)* | 39-week gestation | NA | Age at treatment subtracting risk priod | 5 | 47 | 0.108 | 28 | 2461 | 0.011 | NA | 7.91 (2.64 to 23.71) |
| Liu et al12 | China | Asian | Beijing Tiantan Hospital (1960–2010) | CCOS | Female haemorrhagic bAVMs from 18 to 40 years (n=393)† | Gestation and 6-week postpartum (10 months) | NA | Age at treatment subtracting both risk priod and 18 years | 12 | 361 | 0.033 | 441 | 10 627 | 0.043 | Mantel-Haenszel estimator | 0.71 (0.61 to 0.82) |
| Tonetti et al17 | USA | NA | University of Pittsburgh (1987–2012) | CCOS | Female bAVMs from 15 to 40 years receiving treatment of radiosurgery (n=253)* | 40-week gestation and 12-week postpartum interval | NA | Age at the last follow-up substracting both risk priod and age at radiosurgery | 2 | 18 | 0.111 | 20 | 810 | 0.025 | NA | NA |
| van Beijnum et al18 | Netherlands | NA | VUMC Amsterdam, AMC Amsterdam, Leiden UMC, UMC Utrecht (1990–2006) | CCOS and SCCSS | Female bAVMs from 16 to 41 years (n=95)* | 39-week gestation | NA | Age at treatment subtracting both risk priod and 16 years | 17 | 56 | 0.304 | 78 | 1231 | 0.063 | NA | 6.8 (3.6 to 13.0) for CCOS, 7.1 (3.4 to 13.0) for SCCSS |
| Scotland | SAIVMs (1999–2003, 2006–2010) | Female bAVMs from 16 to 41 years (n=44)* | 3 | 35 | 0.086 | 41 | 597 | 0.069 | NA | 1.3 (0.39 to 4.1) for CCOS, 1.7 (0.0 to 4.4) for SCCSS | ||||||
| Porras et al9 | USA | White (61.1%), black (21.9%), Hispanic (3.3%), Asian (2.2%), other (11.5%) | Johns Hopkins Hospital (1990–2015) | CCOS | Female bAVMs with complete baseline data (n=270)* | 40-week gestation and 6-week postpartum | 6-week abortion and 6-week postabortion period | Age at treatment of AVM or last follow-up subtracting risk priod | 9 | 159 | 0.057 for all patients; 0.070 for patients from 15 to 50 years | 140 | 10 668 | 0.013 for both all patients and those from 15 to 50 years | Poisson regression | 4.43 (1.98 to 8.65) for all patients; 5.61 (2.48 to 11.18) for patients from 15 to 50 years |
| Zhu et al7 | China | Asian | Changhai Hospital (2006–2017) | CCOS | Female bAVMs with complete baseline data (n=264)* | 40-week gestation and 6-week postpartum | 6-week abortion and 6-week postabortion period | Age at treatment of AVM or last follow-up subtracting risk priod | 8 | 148 | 0.054 | 214 | 7336 | 0.029 | Dichotomous variables | 1.90 (0.92 to 3.93) |
| Lee et al14 | USA | White (50.2%), black (10.6%), Hispanic (28.4%), other (10.9%) | SID for California (2005–2011), Florida (2005–2014), New York (2005–2014) | CCOS | Female bAVMs from 15 to 45 years (n=568)* | 40-week gestation and 12-week postpartum | NA | The 52 weeks before pregnancy | 36 | 36 | 0.064 (0.043–0.084) | 11 | 11 | 0.019 (0.008–0.031) | Poisson regression | 3.27 (1.67 to 6.43) |
*Included patients regardless of haemorrhage presentation.
†Included patients with haemorrhage presentation.
bAVMs, brain arteriovenous malformation; CCOS, case–crossover study; NA, not available; RR, relative rate; SAIVMs, Scottish Audit of Intracranial Vascular Malformations study; SCCSS, self-controlled case series study; SID, Healthcare Cost and Utilisation Project State Inpatient Databases; SRS, stereotactic radiosurgery.