October 2003

The five stages of pregnancy: Second trimester

by Dr. Howard Loomis

This installment of my multiple‑part series on the nutrition of pregnancy covers the second trimester. I began, in July, with pre‑conception planning on the part of both the mother and father, stressing how important it is that both of their bodies be healthy and well‑nourished before bringing a child into the world. The following month, I discussed conception and the role fat ingestion, digestion, and assimilation plays in that process. In September's column, I reviewed nutrition in the first trimester of pregnancy and placed great emphasis on the importance of protein ingestion, digestion, and assimilation during that period.

Now, I will describe the sometimes challenging second trimester of pregnancy, highlighted by the baby's first kick. This trimester is challenging for some women because the excitement of becoming pregnant has waned, and everyone is now awaiting the baby's arrival. To make matters worse, the mother‑to‑be begins to lose her figure as she gains weight. She has a difficult time fitting into her clothes, and there are obvious hormonal changes accompanied by the inevitable emotional roller coaster. Those hormonal changes are the focus of this column ‑‑ part four in the series.

Last time, I stressed the importance of protein metabolism during the first trimester and pointed out its preeminent role throughout pregnancy. Well, protein requirements increase even more during the second trimester! Additional protein and calcium are needed to meet the rapid growth of the fetus; the enlargement of the uterus, mammary glands, and placenta; and the increase in maternal blood volume. As I have mentioned in past columns, most females do not tolerate large increases in dietary protein. Even though the demand increases, don't expect their ability to digest protein to improve.

Obviously, calcium intake needs to be increased, not only for calcification of the fetal bones and teeth but also to protect against depletion of maternal calcium reserves. This accounts for the old wives' tale that a woman loses a tooth for every baby she has. Vitamin D enhances the absorption of calcium and plays a major role in calcium metabolism of the fetus, but they are both dependent on protein/fat assimilation.

Pituitary secretion

The anterior pituitary gland directs the endocrine system, and the gland enlarges at least 50 percent during pregnancy. This allows it to increase its production of hormones to stimulate the adrenal and thyroid glands.

Adrenal secretions

There is no way I can overemphasize the need for improved nutritional support of the adrenal glands during pregnancy. In addition to its many hormonal responsibilities before pregnancy, the adrenals now must also make it possible for the placenta to produce enough estrogen and progesterone to maintain the pregnancy and prevent the loss of the fetus. But this process is dependent on the adrenal glands of the mother and the fetus to make an androgenic steroid that is carried to the placenta and converted to estrogen and progesterone. It is imperative that this process be in place by the 12th week to replace the role of human chorionic gonadotrophin.

In addition to preventing spontaneous abortion, these hormones are important for many reasons including loosening the ligaments of the sacroiliac joints and the symphysis pubis and preparing breast tissue for lactation.

Adrenocortical secretion is moderately increased throughout pregnancy. This helps mobilize amino acids from the mother's tissues so they can be used for synthesis of tissues in the fetus: an obvious need for improved protein ingestion, digestion, and assimilation. This probably accounts for another old wives' tale that states the mother loses two years of life for every child.

Aldosterone secretion is increased three‑fold. This causes the retention of excessive amounts of sodium and water, often leading to hypertension. Aldosterone monitors water volume in the extracellular fluids. Since protein also holds water, aldosterone secretion can be reduced significantly with improved protein digestion, thus preventing the occurrence of hypertension.

Secretions by the thyroid gland

The thyroid gland enlarges about 50 percent during pregnancy and increases secretion of thyroxine about the same amount. Apparently, the placenta and the pituitary secrete thyroid‑stimulating hormone. You may recall that the thyroid needs iodine (transported by fatty acids) and protein to make thyroxine. Also, the use of caffeine and white sugar greatly increases the need for additional thyroxine‑a need the mother‑to‑be can hardly meet.

Secretion by the Parathyroid Glands

The parathyroid glands enlarge during pregnancy, especially if the mother is calcium (protein) deficient. This causes calcium resorption from the mother's bones. Parathyroid secretion is greatly increased during lactation because the newborn baby requires much more calcium than it did as a fetus.

It is easy to see how proper nutritional planning should be a part of essential care before, during, and after pregnancy. Unfortunately, it is also easy to see that improved protein and fat ingestion and digestion are seldom part of the planning ‑‑ as this series continues with the third trimester next time.

(Dr. Loomis welcomes input on the subjects covered in this column. To make a comment or ask a question, or for a free copy of his video titled, "Using Enzymes in Clinical Practice: The Loomis System," call 800/662‑2630 or write to him at 6421 Enterprise Lane, Madison, WI 53719. Visit www.loomisenzymes.com online for information on upcoming Loomis Institute seminars.)