The Pregnancy Planner calculates preferred days for getting pregnant. Plans are based on the fact that ovulation happens 14 days before the next menstrual period. If you are trying for a boy or girl, the planner will also suggest some actions that many influence the sex of the child, based on the scientific research of Dr Landrum Shettles and David M. Rorvik, who published findings in a book called "How to Choose the Sex of Your Baby: The Method Best Supported by Scientific Evidence. " As ovulation approaches your chances of getting pregnant increase. Before proceeding, there are a few things to keep in mind: Cycle lengths of more than 35 days are too long for appropriate calculations. Cycle lengths of less than 21 days are too short for appropriate calculations. This calendar cannot be used to reliably prevent pregnancy. Good Luck & Don't Forget to Have Fun! First day of last menstrual period: Select Month Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Select Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 Length of cycle: 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 days Desired Sex of baby: Any Boy Girl Show me: 1 2 3 4 5 6 Months   Here is our Ovulation Calculator Already Pregnant? Need a due date? Or date of conception? Click here for our Pregnancy Due Date Calculator More on Wondertime for Parents