Some cultures held that burying the placenta from a previous birth under a walnut tree would do the trick. One Bengali myth said that intercourse during menstruation on even-numbered days would produce boys, with love-making on odd-numbered days resulting in girls.
奧地利某些地方的人相信把前胎胎盤埋在核桃樹下，可保證下胎生男孩；孟加拉有種迷信，以為在女性月經期中的偶數日行房可生男孩，奇數日則生女；美國部分地區的人仍然深信，行房時將先生褲子掛在床的右邊就可生男。