sequelize associations confusing

I'm using sequelize module for mysql nodeJS. well, i'm creating a database to manage rabbits production in which I use this models:

var rabbit = sequelize.define('rabbit', {
        name: {
            type: Sequelize.STRING
        },
        gender: {
            type: Sequelize.STRING
        },
        birthdate: {
            type: Sequelize.DATE
        },
        origin: {
            type: Sequelize.STRING
        },
        comingdate: {
            type: Sequelize.DATE
        },
        work_group: {
            type: Sequelize.BOOLEAN
        }
    }
);

var birth = sequelize.define('birth', {
        name: {
            type: Sequelize.STRING
        },
        fertdate: {
            type: Sequelize.DATE
        },
        donedate: {
            type: Sequelize.DATE
        }
    }
);
birth.hasMany(rabbit, {as: 'childOf', constraints: false});
birth.belongsTo(rabbit, {as: 'Father', constraints: false});
birth.belongsTo(rabbit, {as: 'Mother', constraints: false});

I explain: every rabbit is related to a birth in which it's born and a birth is related to two rabbits one as father and the other as mother. The question is: what are the getters and setter, I mean if I have a rabbit object "mother" and I do mother.getBirths will it return to birth in which the mother is born or to births of which this rabbit is mother ? And if it returns nothing or I have some errors in my code, how can I get the birth in which rabbit is born ? and how can I get births of a specified mother or father ?

thanks