Are more babies born during a full moon?

// Start with the date you're learning about ($timestamp)

$synmonth = 29.53059;	// Days in a synodic lunar month
$oneday = 24*60*60;	// Seconds in a day
$firstnew = mktime(12,0,0,1,26,1971);	// We happen to know there was a new moon on 26 Jan 1971

$timestamp = $timestamp-$firstnew; // Difference between our timestamp and the new moon

$daysoff = round(fmod($timestamp,$synmonth*$oneday)/$oneday,0);