Many people believe that the woman knows exactly that she would be giving birth to twins. It is a kind of a gut feeling, it is generally said. But, the first possibility of a doctor scientifically confirming that you are, indeed, having twins would be in the sixth week or so after an ultrasound examination.
If the embryos are not clearly visible in the ultrasound, it is quite possible that a Doppler test will help you listen to two separate heartbeats. This is the time when you can start grinning and telling your near and dear ones that you are having twins. But, be forewarned, there is also the possibility of not knowing about the twins until much later if the antenatal care is not good.
Just like everything that differs, pregnancy also differs from woman to woman. The symptoms and the responses of each individual could also differ. So, it is quite possible for the symptoms of carrying twins to be also different. Normally, weight gain could be higher than when you are having a single foetus. You would, certainly, be feeling more ravenous than another pregnant woman who is carrying a single foetus. You would require about 600 additional calories daily than a normal single-foetus carrying a woman.
Aversion towards food, morning sickness, nausea and fatigue would be much more compared to a singleton pregnancy. The frequency of urination would also be more because the uterus exerts more pressure on the bladder as the two fetuses begin to develop internal organs. This is the time when the kidney, liver, brain, spine etc are beginning to develop and the heart begins to beat. Sorry, it is all in plural now. The “hearts” begin to beat.
In short, you will have to have smaller meals more frequently than you would have imagined a woman carrying a single foetus. It also means that you will need to drink more water to keep yourself adequately hydrated. Do not forget, you need to eat for three persons now, you and your twins.