Nowadays we follow a calendar for month. Sometimes the Molad is Friday and they are 2 days of Rosh Chodesh Shabbat and Sunday. The dates are far from the astronomic dates. I am curious to know if Poskim address this regarding Kviut Veset. I was thinking that the svara of Veset Hachodesh is that there is an astronomical periodicity which influences the menstrual cycle. On the influence of the astronomical cycle, the Kviut of Chachamim has also an influence. The Bet Din states the "metsiut" of month. We know the memra of "בתולים חוזרים". If a girl wasn't 3 old because of Ibur Hashana and was raped, the hymen will come back because of the Bet Din statement that she is still not 3 old. Despite this, it seems very strange to state a Rosh Chodesh two days after the Molad and that the menstrual cycle is far from the astronomical cycle, the Beth Din didn't never made a Rosh Chodesh more than one day after the Molad. I am looking for poskim who address this.