In the passage of just 9 months, a microscopic speck has become a baby. At week 7, the embryo is about the size of a grape, weighs a fraction of an ounce, and has webbed, but well-defined toes and fingers. During the fourth month, the fetus doubles in length, to 6 inches, while its weight quadruples to 4 oz. By 5 months, the fetal heart beats between 110 to 160 times a minute and pumps the daily equivalent of 150 qt of blood through its body. By the end of the third trimester, the baby can measure 14 inches from crown to rump and weigh 7-½ lbs or more, taking up nearly every available inch of the womb.

That’s an extraordinary amount of change! And while mom may not sense all of the details of development, she increasingly senses the magnitude of the changes both she and her developing baby are undergoing. For the expectant mother, these changes can involve a full range of physical, psychological, and emotional challenges, as well the growing emotional closeness to her developing baby.

While the physiological changes of pregnancy can be predicted, the psychological, social, and emotional changes are far less programmed. Expectant mothers will share many of the same concerns and feelings, but there are clearly many personal and even cultural components to how women experience pregnancy. Not surprisingly, there has also been no shortage in advice when it comes to counseling mothers-to-be. From ancient times to the present, medical texts and folklore alike have counseled expectant mothers on what they should eat and drink and how they should behave in order to develop desired qualities and traits in their babies while still in the womb.

The most obvious physical changes women will experience are a consequence of the expansion of the uterus. At conception the uterus has only a tiny cavity of 2 tsp or less (10 ml), according to Susan Tucker Blackburn. But over the course of pregnancy, the uterus is transformed into a large, thin-walled structure. At term, the total volume of the contents of the uterus will be 1.3 gal (5 l), 500 to 1000 times the original capacity. In terms that are easier to visualize, Deepak Chopra explains that “the uterus goes from the size of an orange to the size of a watermelon.”

With this expansion of the uterus, the mother undergoes a host of other changes. “There’s a shift in blood flow,” says Chopra. “Her hips widen to create more space and ultimately to create room for the passage of the baby.” There is also a significant increase of 30-40% in circulating blood and plasma volume. (In most cases, however, this increase in blood volume does not raise blood pressure, as might be expected). Oxygen consumption increases 20-30% and total body water can increase up to 2 gal (8 l). “So every step of the way, the mother adapts and accommodates. Everything is exquisitely timed,” says Chopra. “It’s not just an expression of complexity and coordination, it’s an expression of finesse and timing.”

Among the many changes is a shift in the position of internal organs. The expanding uterus causes the liver and intestines to be pushed upward and the stomach to move to a vertical position, rather than its normal horizontal one. The change in the angle of the junction between stomach and esophagus can also contribute to increased acid reflux. Hormonal changes to mucosal capillaries in the respiratory tract can lead to swelling of the lining in the nose, larynx, and trachea, producing symptoms of nasal congestion, voice change, and upper respiratory tract infection. Constipation is a common problem, and the frequency of urinary tract infections can also rise during pregnancy.

Weight Gain
Weight gain, of course, accompanies all healthy pregnancies; 25-30 lbs may be considered optimal, but this can range either higher or lower depending on various factors. (An additional increase in the mother’s weight gain does not necessarily increase fetal weight.) Only a quarter of those added pounds are baby, however. What accounts for the rest of the weight gain? Here’s a breakdown for an average-size woman at 9 months:

Baby	7.5 lbs
Placenta	1 lb
Uterus	2 lbs
Breasts	3 lbs
Blood Volume	4 lbs
Amniotic fluid	2lbs
Extra weight (to maintain healthy pregancy and prep for lactation)	5-10+lbs
____________________________________________	________
Total	29.5+ lbs

Source: Springhill Medical Center, Childbirth Preparation Manual.

Back Pain
Back problems are common during pregnancy and are experienced to some degree by most women.
Back pain or discomfort may be experienced during any point in pregnancy, though it is most common later in pregnancy as the weight of the baby increases.
Back pain during pregnancy can be related to a number of factors:

• Additional weight . The weight gain of pregnancy creates an additional burden on spine and back muscles

• Shift in center of gravity . As the uterus and baby grow, a woman’s center of gravity shifts forward, which causes her posture to change. Poor posture, as well as prolonged standing or bending, can trigger or exacerbate pain or discomfort
• Increase of hormones . Hormones released during pregnancy relax ligaments and loosen joints in the pelvic area in preparation for birth, but this can also affect back support
• Stress . Stress has a knack for finding the weak spot in the body. Pregnancy and the changes it produces in the pelvic area can exacerbate problems for women with a prior history of back pain

More on this topic

Mother-Baby Bond: The Biology of Love (VIDEO)
Mother-Baby Bond: The Biology of Love
Establishing New Life
Nurture & Protect
Growth & Sensations
Adapting & Anticipating
Joyous Mom, Joyous Baby
Your Baby Enters the World
Nourishing Body & Bond
Mother & Teacher
Nurturing Development
A Mutual Gaze
From Bump to Bundle

Related Health Centers:

Infant Nutrition Health Center, Mother-Baby Bond Health Center, Mother’s Milk Health Center, Monthly Infant Development Calendar Health Center,Weekly Pregnancy Calendar Health Center