YearMultiparous MothersInterpregnancy Interval
Short IPIIPI of 12-35 MonthsIPI of 36 Months and over
NumberRateNumberRateNumberRate
Number & Rate of Live Births by Interpregnancy Interval and by Year,
St. Clair County, Michigan 1989-2015
19891,201  205  170.7603  502.1393  327.2
19901,200  228  190.0583  485.8389  324.2
19911,033  199  192.6483  467.6351  339.8
1992971  185  190.5480  494.3306  315.1
19931,192  230  193.0558  468.1404  338.9
19941,187  232  195.5551  464.2404  340.4
19951,211  243  200.7546  450.9422  348.5
19961,127  200  177.5512  454.3415  368.2
19971,115  204  183.0506  453.8405  363.2
19981,129  188  166.5496  439.3445  394.2
19991,116  169  151.4512  458.8435  389.8
20001,174  184  156.7559  476.1431  367.1
20011,050  165  157.1498  474.3387  368.6
20021,144  203  177.4558  487.8383  334.8
20031,143  209  182.9528  461.9406  355.2
20041,126  233  206.9499  443.2394  349.9
20051,072  214  199.6497  463.6361  336.8
20061,144  225  196.7525  458.9394  344.4
20071,135  235  207.0478  421.1422  371.8
20081,057  215  203.4478  452.2364  344.4
2009973  186  191.2471  484.1316  324.8
2010894  177  198.0387  432.9330  369.1
2011893  147  164.6404  452.4342  383.0
2012852  139  163.1389  456.6324  380.3
2013844  148  175.4390  462.1306  362.6
2014877  159  181.3379  432.2339  386.5
2015885  146  165.0382  431.6357  403.4

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;1990-2015 Geocoded Michigan Birth Certificate Registries.
Division for Vital Records & Health Statistics, Michigan Department of Health & Human Services