omphalomancy

from The Century Dictionary.

• noun Divination by means of the number of knots in the navel-string of a child—a fancied indication as to how many more children its mother will have.

from the GNU version of the Collaborative International Dictionary of English.

• noun Divination by means of a child's navel, to learn how many children the mother may have.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun divination by means of a child's navel, to learn how many children the mother may have.