Number & Rate of Live Births by Interpregnancy Interval and by Year,
Wayne County, Michigan 1989-2023

Year	Multiparous Mothers	Interpregnancy Interval
		Short IPI		IPI of 12-35 Months		IPI of 36 Months and over
		Number	Rate	Number	Rate	Number	Rate
1989	17,320	3,598	207.7	7,188	415.0	6,534	377.3
1990	16,017	3,776	235.7	6,529	407.6	5,712	356.6
1991	10,696	2,680	250.6	4,210	393.6	3,806	355.8
1992	9,489	2,306	243.0	3,937	414.9	3,246	342.1
1993	20,570	4,992	242.7	8,706	423.2	6,872	334.1
1994	19,362	4,428	228.7	8,009	413.6	6,925	357.7
1995	17,847	3,635	203.7	7,474	418.8	6,738	377.5
1996	17,118	3,190	186.4	7,326	428.0	6,602	385.7
1997	17,532	3,244	185.0	7,207	411.1	7,081	403.9
1998	17,128	3,092	180.5	6,899	402.8	7,137	416.7
1999	16,619	2,893	174.1	6,728	404.8	6,998	421.1
2000	17,289	3,114	180.1	6,982	403.8	7,193	416.0
2001	17,185	3,089	179.7	6,936	403.6	7,160	416.6
2002	16,304	2,831	173.6	6,715	411.9	6,758	414.5
2003	15,921	2,943	184.9	6,367	399.9	6,611	415.2
2004	15,411	2,674	173.5	6,332	410.9	6,405	415.6
2005	14,972	2,768	184.9	5,924	395.7	6,280	419.4
2006	15,013	2,729	181.8	5,979	398.3	6,305	420.0
2007	13,828	2,528	182.8	5,501	397.8	5,799	419.4
2008	12,692	2,389	188.2	5,033	396.5	5,270	415.2
2009	12,715	2,334	183.6	5,019	394.7	5,362	421.7
2010	12,630	2,261	179.0	5,097	403.6	5,272	417.4
2011	12,975	2,326	179.3	5,111	393.9	5,538	426.8
2012	12,752	2,197	172.3	5,155	404.3	5,400	423.5
2013	13,042	2,243	172.0	5,192	398.1	5,607	429.9
2014	12,939	2,253	174.1	5,090	393.4	5,596	432.5
2015	13,766	2,438	177.1	5,411	393.1	5,917	429.8
2016	13,773	2,394	173.8	5,469	397.1	5,910	429.1
2017	13,922	2,391	171.7	5,537	397.7	5,994	430.5
2018	13,701	2,386	174.1	5,399	394.1	5,916	431.8
2019	13,429	2,391	178.0	5,230	389.5	5,808	432.5
2020	12,923	2,255	174.5	5,084	393.4	5,584	432.1
2021	12,477	2,151	172.4	4,978	399.0	5,348	428.6
2022	12,084	2,033	168.2	4,789	396.3	5,262	435.5
2023	11,059	1,960	177.2	4,354	393.7	4,745	429.1

Notes:

Rates are per 1,000 multiparous mothers.

Inter-pregnancy Interval (IPI) is the time in months between the date of last menstrual period of current pregnancy and the date of previous live birth among multiparous mothers. (This definition of IPI is sometimes called the "birth-to-birth interval, minus 9 months.")

Short IPI

The IPI is less than 12 months.

Source: 1989 Michigan Birth Certificate Registry;1990-2023 Geocoded Michigan Birth Certificate Registries.
Division for Vital Records & Health Statistics, Michigan Department of Health & Human Services