Me: I was planning on moving onto another subject in my posts when Tyler sent me a message asking if I could do slightly more research on what could be causing these women to get taller. So here is my attempt to understand and guess at the cause.

What we know right now is that there is a decent percentage of women who found that they have grown in height during and after pregnancy. If I was to take a guess at the rate or percentage, it could be as low as 1 out of 10,000 women or even as high as 1 out of every 100 women, so my guess is that it is probably around 0.01%-1% . I don’t believe that this type of thing can happen that much more prevalently. However, any case of height increase in anyone past the normal age of maturity is an interesting case to look into.

Feet Size Increase

What we know is that the phenomena of feet expanding and the need to buy bigger shoes is a commonly cited and found in pregnancy guides. If it was really just the muscle relaxing, then it should only cause the feet to get wider, not longer. However there are women who said that their shoe size went up by 2-3 sizes. Most women’s shoes that I know have also extra wide variations. This means that technically women don’t need to switch to a higher size, since size is defined by length, not wide. The width of one’s feet can be switch in shoes with Extra Wide pairs. Of course we could say that the feet just got proportionately bigger, in width and length. That would make more sense but the increase of shoe size by 3 shoe sizes is beyond what i could imagine swelling can do, especially since the feet never shrink back in size after the pregnancy. 1 shoe size increase is about 0.5 cm in extra length. That means that a 3 size increase is a 1.5 cm increase in feet length. From the picture on the right (found from source HERE) I guess it might be possible for the feet’s ligaments to relax enough to cause even 1 cm of length increase.

Hands Size Increase

From links like HERE we know that many women during pregnancy can’t wear their wedding rings. Since the ring must always overcome the diameter of the knuckle joints, it makes sense that what is really blocking the fingers from the ring are the knuckles. The knuckles have become swollen and enlarged. If the entire finger has swelled , then that is the result of the muscle relaxant. If the reason the ring can’t get there is only from the knuckles, we can say that the pregnancy is doing something to the joints, specifically the cartilage at the synovial joints in the metacarpals of the hands. Using this type of logic we can say that it is possible the height increase was from a pregnancy induced swelling of the articular cartilage on synovial joints in general. It is a very common thing for pregnant women to notice pain and swelling in their ankles and wrists.

Height Increase

If we assume the hormone/endocrinology reason for the height increase, we have to see what types of hormones could cause this. From this link HERE…we can see a list of all the major hormones which are involved in pregnancy.

Hormones	Secretion by	Main function (effect of hormone)
Progesterone	Chorion after 6 weeks Corpus Luteum in first 3-4 months Placenta after 3 months	Maintains lining of uterus for implantation Prepares mammary glands for lactatio Stimulates aldosterone secretion from adrenal cortex
Oestrogen	Chorion after 3-4 weeks Corpus Luteum in first 3-4 months Placenta after 3 months	Works with progesterone for endometrium maintenance and mammary gland preparation Increases protein synthesis Lowers blood cholesterol level Inhibits action of prolactin on mammary glands
HCG	Chorion directly after implantation sharp increase -> peaks at 9 weeks -> decreases until birth	Stops degeneration of corpus luteum Acts as an indication of pregnancy in urine sample pregnancy tests Allows gonadotropins to enter the foetal blood to premote sexual differentiation of the foetus
Relaxin	Corpus Luteum Placenta after 3 months	Increases flexibility of pubic symphysis and ligaments of pelvis Relaxation of Myometrium Dilates cervix during labour
HPL	Chorion	Allows active transport of amino acids and glucose from maternal to the foetal blood Makes free fatty acids available for the mother as an energy source Prepares mammary glands for lactation
CRH	Placenta	Timing of birth Stimulates adrenal cortex to secrete cortisol and aldosterone
Anterior Pituitary Hormones	Presence of progesterone and oestrogen	Increase prolactin secretion- stimulates milk secretion Decrease growth hormone secretion Decreases ACTH and TSH (gonadotropins) secretion

What I notice right away is that the Progesterone and O-estrogen are produce from the same location as Natural Growth Hormones. However it is also noted that during pregnancy the GH secretion decreases.

Note: What is critical to realize is that during pregnancy most women are not thinking about their height at all so even if they did increase in height, they would never realize it since they are too preoccupied with other issues, like pain, swollen joints, nausea, mood swings, etc. Height is the last thing on a pregnant woman’s mind. This might pin-point to the idea that it could be that height  increase might be slightly more common than reported. 

 

If we use the diagram on the left (from HERE) we notice that the Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) are both produced from the pituitary gland at around the anterior pituitary region just like the GH pathway.

I remember that the FSH is a type of growth hormone. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the body.

Using the wiki article on FSH located HERE we see that high levels of FSH can lead to Klinefelter’s syndrome. What is amazing is that I have found a few PubMed articles that show that people who have Klinefelter’s syndrome exhibit tall stature. I was actually going o write up a post relating Klinefelter’ syndrome with height since there is a big connection.

From the diagram on the right (found HERE) we can see that the release and rate of release of the major hormones during the time intervals of pregnancy, assuming a 9.5 month gestation cycle.

I am going to have to use a little bit of elementary physics to explain my reasoning for the next part. In general, the way many phenomena can be explained in nature is through differential equations, which one can solve usually using approximation methods to model dynamic behavior of the world around us. This is why the exponential function is so commonly seen in nature, since the differential and integral function of the exponential is the exponential itself.

Both newton’s original motion laws and einstein’s general theory of relativity showed that a rate that is constant will not produce changes, but require a change in rate.

When looking at this diagram, I would guess that the only time and range which height increase probably would happen is during a interval where the hormone release rate increased, which implies a change of a change, or an acceleration. Looking at the diagram, I really have only one small fact to go off of which is that one mother said that her height was measured from the 12th week with no height change and her height was measured in the 22 week and she saw an increase of 2.5 inches. If we look at the graph to see whether there are any hormones which saw an increase in rate of release (aka acceleration) which in calculus terms is what is known as a concave inflection point moving upwards. The graphs seems to suggest that it is either the O-estrogen or the progesterone.

Note: I will look at the possible connection between progesterone and o-estrogen and height and growth in another post. 

From this ParentDish.Co we learn that during pregnancy a lot of the Calcium in the mother’s system gets absorbed by the baby. Teeth loss and bleeding gums are very common. This might help explain the height increase. Maybe one of the only ways to increase height is to make the bones weaker by removing the calcium hypoxilates. from the same source link I quote this “Rachel agrees: “My ribcage expanded after my first pregnancy, and some of my bras and dresses are too tight across there now.””. This seems to suggest that maybe the hormones can get into whatever cartilage or even bones and get them to get bigger somehow. We learned from a previous post that the cartilage in the sternum ossify far later than the growth plate cartilage in the limbs. This women might have had her cartilage in the sternum increase in size.

Further Analysis: From using what little information I could gather, it seems that women who experience the height increase are usually shorter than average with the forum posts saying they were around the 5’0-5’3″ mark. One women said it was not her torso which increased in length. Many said they say height gain in their 3rd pregnancy, others in their first pregnancy. One commented her height increase happened only when she was giving birth to her only daughter. One women said that her gain was around the 12-22 week time period.

Theory 1: If I was to guess I would say that the phenomena is actually catch up growth at work. These women who are shorter than average had stunted growth. Since O-estrogen and progesterone has been used in traditional history for tall girls to stop growth, they are just like extrados and estrogen. They cause a boost in the aging process of growth plates. I can assume that the growth plates for the short females never fully sealed. The increase shot of progesterone and o-estrogen release into the body caused the growth plates to give the last lurch in longitudinal growth from whatever chondrocytes were still around the little bit of growth plate that was left.

Theory 2: The edema they develop causes so much extra water to go into their synovial joints swelling everything up. The swelling of water (in knees and ankles) gets into the articular cartilage. Remember that salt causes edema to happen since the water molecule moves from higher water concentration to lower water molecule concentration (from source HERE). Somehow one of the pregnancy hormones gets more salt into the cartilage and the water goes in the cartilage causing it to expand. The expansion might get into any chondrocytes in the articular cartilage and get them to hypertrophy which floats randomly and sometimes get to the one epiphysis bone surface. The progesterone comes along and takes some of the chondrocytes and ossify them leading to longitudinal growth. Of course this is all assuming that there are still come chondrocytes still in the articular cartilage and the randomness is not completely random but is more prone to land on the bone surface, and that the blood vessels supplying to the cartilage ends can reach to the hypertrophic chondrocytes.