Table 1

Summary of studies investigating the incidence of asthma exacerbations during pregnancy

Study	Country	Year	Study design	Asthma (n)	% hospitalised	% ED visits	ICS use	Suspected causes of exacerbation
ED, emergency department; ICS, inhaled corticosteroid; OCS, oral corticosteroid.
Williams³	UK	1955–65	Case series	n = 23	100%		Nil	Nasorespiratory infection
Gluck and Gluck⁴	USA		Case series	n = 47	28%		Nil
Melville et al⁵	Jamaica and Trinidad		Case series	Unknown	n = 8		Unknown
Stenius-Aarniala et al⁶	Finland	1972–82	Prospective cohort	n = 198	17%		Some used ICS (up to a maximum dose of 400 μg/day)
Schatz et al⁷	USA	1978–84	Prospective cohort	n = 330	1.8%	10.9%	10% used beclomethasone
Apter et al⁸	USA	1978–88	Case series	n = 28	64%	43%	29% used ICS	Discontinuation of medication
								Viral infection
Mabie et al⁹	USA	1986–9	Case series	n = 200	42.5%	13%	Nil
Perlow et al¹⁰	USA	1985–90	Historical cohort	n = 81	46%		Unknown
Jana et al¹¹	India	1983–92	Prospective cohort	n = 182	8.2%		Some used beclomethasone
Schatz et al¹²	USA	1978–89	Prospective cohort	n = 486		11.1% received nebulised bronchodilators in clinic or ED	8% used beclomethasone
Stenius-Aarniala et al¹³	Finland	1982–92	Prospective and retrospective cohort	n = 504	6.5%	3%	ICS used by 34% of those who had an exacerbation and 62% of those who did not have an exacerbation	Lack of ICS use
Dombrowski et al¹⁴	USA	1992–5	Historical cohort	n = 54	43%		26% used beclomethasone
							28% used triamcinolone acetonide
Kurinczuk et al¹	Australia	1995–7	Cross sectional survey	n = 79		62% had an “asthma attack or wheezing” during pregnancy	Unknown
Henderson et al¹⁵	USA	1960–5	Prospective cohort	n = 1574	2.2%		Nil
Hartert et al¹⁶	USA	1985–93	Historical cohort	n = 2461	6%(during influenza season)		Unknown	Influenza
Schatz et al¹⁷	USA	1994–9	Prospective cohort	n = 1739 overall	5.1% overall
				n = 873 mild	2.3% mild		No ICS (mild)
				n = 814 moderate n = 52 severe	6.8% moderate 26.9% severe		Some ICS use (moderate and severe)
Namazy et al¹⁸	USA	1996–2002	Case series	n = 451		7.6% had an “acute attack”	100% ICS use
Martel et al¹⁹	Canada	1990–2000	Nested case-control study	n = 3315	13% ED or admission		46% used ICS
Carroll et al²⁰	USA	1995–2001	Historical cohort	n = 4315	6.3%	11.1%	16%
Bakhireva et al²¹	North America	1998–2003	Prospective cohort	n = 654	2.5%		67% used ICS without OCS
Otsuka et al²²	Japan	1987–2003	Historical cohort	n = 592		1.38% had “asthma attacks” during labour and delivery	55.3%
Schatz and Liebman²³	USA	2000–1	Historical cohort	n = 633	0.2%	3.8%	16% before pregnancy, 10% during pregnancy	Not using ICS before pregnancy
Murphy et al²⁴	Australia	1997–2003	Prospective cohort	n = 146	8.2%	2.7%	64% used ICS	Viral infection
Murphy et al²⁴	Australia	1997–2003	Prospective cohort	n = 146	8.2%			Non-adherence to ICS