It’s a miracle that women are able to form a person from a ball of cells which can then be pushed out of a hole that is tiny in comparison. Therefore, I decided to research what it is that makes this reproduction possible.
The story that all teenage girls are taught during sex-education classes is that women can give birth because they have wider hips and women that have slightly smaller hips are now more commonly told that they can’t have a natural birth or that their natural birth will be more laboured or longer in duration is slightly untrue. This is because doctors can’t measure how much the head of the baby will mold as it squeezes out of the pelvis because the bones in the baby’s head are made to overlap during the birth and the female pelvis can relax to accommodate the size of the baby’s head. Also, there are four joints that join different pelvic bones together and during pregnancy and labour, a hormone called relaxin softens the ligaments and this allows the pelvis to stretch and widens the cervix. Relaxin is produced by the ovary and, during pregnancy, the placenta.Early on in pregnancy, relaxin inhibits contractions in the uterus wall which prevents premature childbirth. The enzyme also regulates cardiovascular and renal systems in order to keep up with the demand of oxygen and other nutrients for the foetus (like folic acid and iron) and to also get rid of waste products. This is possible because of how relaxin can dilate the blood cells in women which increase blood flow to the placenta and kidneys, the organs that filter the blood and form urine.
There has also been recent research that shows that women carry most of the baby’s weight on their back bone and as the foetus gets larger and larger, women extend their spine so that the upper body moves backward, which increases the curve of the lower back. This allows more support to be given by the back bone which would otherwise be put on the back muscles. The entire idea of the female back curving closer and closer to labour is possible because the female vertebrae are shaped like wedges which act in a similar way to the wedges in arches or bridges. Men have fewer of these wedge-like shapes and so wouldn’t be able to sustain this essential curve for nine months.
The time period may be another adaptation because by six months of pregnancy women spend twice their energy in order to keep metabolic processes going and this cost continues as the pregnancy continues and so new research implies that the labour does not begin because of some “pelvic limit” but because the mother’s body can no longer supply the substances that the baby needs to continue to grow and the mother needs to survive. The pelvis and baby size then adapts to this metabolic limit.
Women also have more body fat than men, 18-20% compared to 10-15% in men. This is in anticipation to nourish the foetus and the energy that is needed during pregnancy as stated above. Oestrogen is the hormone that reduces women’s ability to burn food after eating, this is the only reason that women have ‘slower’ metabolisms than men. Women produce ten times as much oestrogen as men which allows women to perform better than their male counterparts in endurance which is pretty important for the nine month marathon of pregnancy as well as the time afterwards.
Studies show that women’s brains have more nerve cells packed in and a thicker corpus callosum (the row of fibres that connect two cerebral hemispheres) and so women are able to transfer data from left to right of their brains quicker than men; this has nothing to do with intelligence but allows women to comprehend a larger range of emotions in their babies generally.
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