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Week 9 If you've just found out you're pregnant, you might want to start by reading the previous sections. How Big Is Your Baby? The crown-to-rump length of the embryo is 0.9 inch to 1.2 inches (22 to 30mm). This is close to the size of a medium green olive. How Big Are You? Each week your uterus grows larger with the baby growing inside it. You may begin to see your waistline growing thicker by this time. A pelvic exam will detect a uterus a little bigger than a grapefruit. How Your Baby Is Growing and Developing If you could look inside your uterus, you'd see many changes in your baby. The illustration on page 88 shows some of them. Your baby's arms and legs are longer. Hands are flexed at the wrist and meet over the heart area. They continue to extend in front of the body. Fingers are longer, and the tips are slightly swollen where touch pads are developing. The feet are approaching the midline of the body and may be long enough to meet in front of the torso. The head is more erect, and the neck is more developed. The eyelids almost cover the eyes. Up to this time, the eyes have been uncovered. External ears are evident and well-formed. Your baby now moves its body and limbs. This movement may be seen during an ultrasound exam. The baby looks more recognizable as a human being, although it is still extremely small. It still is probably impossible to distinguish a male from a female. External organs (external genitalia) of the male and female appear very similar and will not be distinguishable for another few weeks. Changes in You Weight Gain Most women are very interested in their weight during pregnancy; many watch their weight closely. As strange as it may seem, gaining weight is an important way to monitor the well-being of your developing baby. Even though your weight gain may be small, your body is changing. See the chart on the next page.
Beatrice was upset when she came to my office. She had heard she would gain between 25 and 35 pounds during her pregnancy, but she didn't want to be ôthat fat.ö I told her, ôChanges to your bodyùincreased size of the uterus, breast tissue, blood volume and body fluidùaccount for the largest part of your weight gain. To support a pregnancy, your body stores nutrients and increases the volume of blood and other fluids it produces. One reason for the extra fat is to prepare you to produce milk for breastfeeding.ö She felt better knowing that the weight she gained was for the good of the baby. Increased Blood Volume Your blood system changes dramatically during pregnancy. Your blood volume increases greatlyùto about 50% more than before you became pregnant. However, this amount varies from woman to woman. Increased blood volume is important. It is designed to meet the demands of your growing uterus. This increase does not include the blood in the embryo, whose circulation is separate (fetal blood does not mix with your blood). It protects you and your baby from harmful effects when you lie down or stand up. It is also a safeguard during labor and delivery when some blood is lost. The increase in blood volume starts during the first trimester. The largest increase occurs during the second trimester. It continues to increase at a slower rate during the third trimester. Blood is composed of fluid (plasma) and cells (red blood cells and white blood cells). Plasma and cells play an important role in your body's function. Fluid and cells increase to different degrees. Usually there is an initial rise in plasma volume followed by an increase in red blood cells. The increase in red blood cells increases your body's demand for iron. Red blood cells and plasma both increase during pregnancy; plasma increases more. This increase in plasma can cause anemia. If you're anemic, especially during pregnancy, you may feel tired, fatigue easily or experience a general feeling of ill health. (See Week 22 for a discussion of anemia.) How Your Actions Affect Your Baby's Development During pregnancy, nearly every woman worries whether her baby will be perfect. Most women worry unnecessarily. Major birth defects are apparent in only about 3% of all newborns at birth. Of those 3%, are causes of these abnormalities known? Could they have been prevented? Abnormal Fetal Development Teratology is the study of abnormal fetal development. An exact cause or reason for a birth defect is found in less than half of all cases. Obstetricians and other doctors providing care to pregnant women are often asked about substances (teratogens) that may be harmful. We believe some agents may be harmful, but researchers have not been able to prove this. However, other agents have been proved to be harmful. Some agents cause major defects if exposure occurs at a specific, critical time in fetal development. But they may not be harmful at other times. Once major development has been completed in the fetus, usually by the 13th week, the effect of a certain substance may be only growth retardation or smaller organ size rather than large structural defects. One example is rubella. It can cause many anatomical defects, such as heart malformations, if the fetus is infected during the first trimester of pregnancy. A rubella infection occurring later is less serious. Individual Response to Exposure There is a great deal of individual variation in response to the size of a dose of an agent and to particular agents. Alcohol is a good example. Large amounts appear to have no effect on some fetuses, while other fetuses may be harmed by low amounts. Animal studies provide much of our information about possible harmful agents. This information can be helpful but cannot always be applied directly to humans. Other information comes from situations in which women were exposed who did not know they were pregnant or who did not know a particular medication could be harmful. Information gathered from these instances is difficult to apply directly to a particular pregnancy. A list of known teratogens and the effects they may have on an embryo or fetus follows. If you have taken any of these substances, discuss them as soon as possible with your doctor for your peace of mind. If testing or follow-up is necessary, your doctor will advise you. Effects of Medications and Chemicals on Your Baby Many substances can affect the your baby's early development. Below is a list of some medications and chemicals, and their possible effects on a developing baby. Drugs and Chemicals Effects on Fetus Alcohol Growth and mental retardation Microcephaly Various major malformations Androgens Ambiguous genital development (male hormones) (depends on dose given and when given) Anticoagulants Bone and hand abnormalities (warfarin) Intrauterine-growth retardation Central-nervous-system and eye abnormalities Antithyroid drugs Hypothyroidism (propylthiouracil, iodide, Fetal goiter methimazole) Chemotherapeutic drugs Increased risk of miscarriage (methotrexate, aminopterin) Diethylstilbestrol (DES) Abnormalities of female reproductive organs Female and male infertility Isotretinoin Increased miscarriage rate (Accutane) Nervous-system defects Facial defects Cleft palate Lead Increased miscarriage and stillbirth rates Lithium Congenital heart disease Organic mercury Cerebral atrophy Mental retardation Spasticity Seizures Blindness Phenytoin Growth retardation (Dilantin«) Mental retardation Microcephaly Streptomycin Hearing loss Cranial-nerve damage Tetracycline Hypoplasia of tooth enamel Discoloration of permanent teeth Thalidomide Severe limb defects Trimethadione Cleft lip Cleft palate Growth retardation Miscarriage Valproic acid Neural-tube defects X-ray therapy Microcephaly Mental retardation Leukemia (Modified from A.C.O.G. Technical Bulletin #84, Teratology, February, 1985, American College of Obstetricians and Gynecologists) You Should also Know Effects of Infections on Your Baby Some infections and illnesses a woman contracts can also affect her baby's development during this growth period. Below is a list of some infections and diseases, and the effects they may have on a developing baby. Infections Effects on Fetus Cytomegalovirus (CMV) Microcephaly Brain damage Hearing loss Rubella Cataracts (German measles) Deafness Heart lesions Can involve all organs Syphilis Fetal death Skin defects Toxoplasmosis Possible effects on all organs Varicella Possible effects on all organs
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