HCG and estrogen are the common pregnancy hormones which most of us would be aware off. They do help in maintaining your pregnancy and help to prepare you for childbirth. So let us now go through some pregnancy hormones that you need to be aware about Oxytocin This is the hormone of sexual reproduction along with social bonding. This hormone has an important role to play during pregnancy along with childbirth. This would even stretch over to the final year once the delivery is over. The presence of this hormone during the first trimester of pregnancy does go on to predict the bonding behaviour between moms and kids. In the starting phase of pregnancy the contraction of the uterus does take place due to the rising levels of this hormone. Once you reach the last stage of delivery when the baby is born the function of this hormone would be to ensure that the uterus does keep on contracting which would mean that the placenta would be pushed out of the uterus. You are going to cordon off the blood vessels that are attached to it and then the uterus does shrink back to its normal size. When higher levels of this hormone are found it is going to encourage mutual attachment between mothers and the would be babies. Prolactin This goes by the name of the milk production hormone. The levels of this hormone increase by 10 to 20 times during the course of pregnancy and for lactation you are going to prepare the breast tissues. Once the baby is born the levels of this hormone go on to increase and at this point of time the production of milk starts. In order to keep this level of hormone intact and to ensure better production of milk you might need to pump or breastfeed. Any actions that you are going to undertake is going to stimulate the levels of this hormone and in the process forces the milk glands to produce more and more milk. Relaxin The mere presence of this hormone points to the fact that you would need to loosen up. This is present in your body and even when you do not happen to be pregnant but all this at a much lower level. When does relaxin peak during pregnancy is an interesting fact. An answer to when does relaxin peak in pregnancy would mean that it would be the first trimester of pregnancy. It would help with the growth along with the implantation of the uterus and through contraction of the uterus would prevent any form of preterm birth. It also performs the task of regulating your renal or cardiovascular systems and this would enable them to cope up with the extra work that is expected during the course of pregnancy. Once you reach the fag end of pregnancy this would rupture the various membranes and helps you to prepare for delivery by softening the vagina and the cervix.