Determining the Gender of a Fetus in a Pregnant Woman

Original Text

诀曰：

父母岁数两头安，受胎之月中心取；乾坎艮震为男儿，巽离坤兑总属女。

假父母年双为折，受胎月只为单，成坎卦，定男；父母年只为单，受胎月双为拆，成离卦，定女。父年上，母年下，胎月中，馀准此推。

又一法：以大衍之数推之，诀曰：

七七四十九，问娘何月有；除却母生年，单奇双是偶；奇偶若不常，寿命不长久。

假先下四十九数于算盘，乃加上母受胎月数，总得若干数。若值正月胎，是五十数，其母三十一除去，止馀十九数，九则为单，单则男。若单生女，双生男，主夭折。

Interpretation

The formula says:

The ages of the parents should be evenly accounted for at both ends, and the month of conception should be taken as the middle reference; Qian, Kan, Gen, and Zhen in the Eight Trigrams indicate a male child, while Xun, Li, Kun, and Dui always represent a female child.

Suppose the sum of the parents' ages is an even number, and the month of conception is an odd number. This forms the trigram of Kan, indicating a male child. If the sum of the parents' ages is an odd number and the month of conception is an even number, it forms the trigram of Li, indicating a female child. Take the father's age as the upper part, the mother's age as the lower part, and the month of conception as the middle part. The rest can be deduced accordingly.

Another method: Use the numbers in the Grand Yielding Calculation to make deductions. The formula says:

Multiply seven by seven to get forty - nine. Ask when the mother conceived. Subtract the mother's age at the time of birth. If the result is odd, it's one thing; if it's even, it's another. If the odd - even rule doesn't hold, the lifespan will not be long.

First, set the number 49 on the abacus, then add the number of the month when the mother conceived. Calculate the total number. If the conception occurred in the first lunar month, the total is 50. Subtract the mother's age (31 in this case) from it, leaving 19. Since 9 is an odd number, an odd number indicates a male baby. If an odd number indicates a female baby and an even number indicates a male baby, it means the baby will die prematurely.