Birth rates and the Phase of the Moon

AAS Poster Materials,
Jan. 2002 DC Meeting

D.Caton Homepage


It is a widespread belief that more births occur during the full moon than at other phases. Is that true? We are studying this question and extending an earlier study which suggested otherwise.

The original study found a weak correlation of births with lunar phase, as shown in the above plot. Here are the residuals from the mean number of births for each day of the lunar cycle. Day 1 is the new moon and full moon occurs about day 14.75. These earlier results show a minimum at the new and full phases and a maximum at third quarter. A minimum occurs at first quarter.

See the January 2002 DC Meeting poster link at left for components of a poster presented at the AAS with the final results.