[ Editorials | Departments and Series | Index ]

Preconception Screening and Counseling

Cathryn Heath, MD; Rhina Acevedo, MD

Any primary care physician who sees women for "well" gynecologic visits is likely to get requests for information about increasing the chance for a healthy pregnancy. Although approximately 50% of pregnancies are unintended, the remainder are planned.¹ The preconception visit can optimize a woman's health status prior to pregnancy, and educate her about the health risks and effects during the first trimester. Even physicians who do not practice prenatal/obstetric care should be able to provide preconception counseling to their patients. This article discusses preconception screening utilizing the medical history, physical examination, and laboratory tests, including genetic testing. Preconception health-risk counseling will be addressed as well.

HISTORY

If the patient has visited the physician previously, many aspects of her health history may already be on record.

Pregnancy History

The pregnancy history should include the number of pregnancies, outcomes, spontaneous and elective abortions (including estimated gestational age at termination), number of preterm infants, and number of living children. If a patient has had one or more second-trimester pregnancy losses, she might be considered at high-risk. Preterm pregnancies are also considered high-risk, as 17% to 38% of women with prior preterm deliveries will deliver prematurely again.² Additional information, such as the size(s) of the infant(s) and any problems that arose during previous pregnancies, can help to determine what could happen during the next pregnancy.^3,4

Gynecologic History

Last menstrual period, length of cycle, length of menses, and age at menarche can give important information about the patient's estimated date of confinement. Gynecologic infectious disease history, including abnormal Papanicolaou (Pap) smears and history of venereal warts, herpes, or other sexually transmitted diseases, is also relevant; women with a history of gonorrhea and/or chlamydia are at higher risk of ectopic pregnancy. It is important to offer to screen women and their partners for human immunodeficiency virus (HIV), which can be transferred to the infant.

Surgical History

Cesarean delivery and any other gynecologic procedures (eg, cone biopsy) may also alter the course of pregnancy, and should be discussed. Women who have undergone cervical conization for invasive cervical carcinoma are at an increased risk for preterm delivery, and are therefore considered high-risk in terms of pregnancy.⁵

Medical History/Medications
Both past and current medical conditions should be elicited, especially with regard to controlling known medical diseases prior to pregnancy. For example, changing a hypertensive woman's medication from an angiotensin converting enzyme inhibitor to an a-adrenergic medication or a calcium channel blocker prior to pregnancy would decrease her risk by switching from a pregnancy category D drug to a category B drug. Diabetic women should optimally use insulin, as opposed to an oral antidiabetic agent. Women using medications that have been classified as pregnancy category X (eg, isotretinoin, warfarin, many anticancer agents) should be counseled to consider alternative medications or not to become pregnant. Requesting a list of medications—including over-the-counter and vitamin/herbal preparations—can promote useful discussion about which agents are safe during pregnancy and which should be avoided.

Family History

The family history, particularly the maternal history, may provide the practitioner with clues about possible pregnancy complications and patient concerns. Questioning whether other family members have had multiple gestations or genetic abnormalities is also a useful screen for familial genetic defects. This may help identify patients who need formal genetic counseling prior to pregnancy, or as early as possible in their current pregnancy.

Social History

Determining past/current use of cigarettes and nicotine equivalents, alcohol, and illicit drugs is an important component of the preconception examination. Interventions to stop smoking are effective during pregnancy, and a woman's desire for a healthy child may motivate her to change unhealthy behaviors.⁶ Also, a discussion about the value of exercise may increase the likelihood of a positive change in personal habits. The woman's occupation may increase her risk of miscarriage; patients who work with chemical substances such as lead and mercury must understand that these agents may cause spontaneous abortions.^7,8 As domestic violence often escalates during pregnancy, screening women prior to pregnancy may allow the woman to confide in the physician about a potentially dangerous situation and receive help prior to pregnancy.⁹

back to top

PHYSICAL EXAMINATION

A complete physical examination, including vital signs and thyroid, breast, gynecologic, and cardiac evaluation, should be performed. Specifically, it is useful to know whether a woman has a heart murmur prior to pregnancy, as most such patients develop flow murmurs during gestation. Breast masses must be assessed promptly, as pregnancy may result in a delay of diagnosis and/or treatment of breast cancer.¹⁰ A pelvic examination with a Pap smear and cultures for gonorrhea and chlamydia should be performed. The bimanual examination reveals any sign of uterine or ovarian enlargement or an abnormally shaped uterus, which can then be evaluated prior to pregnancy.

back to top

LABORATORY EVALUATION

The basic laboratory evaluation is best done prior to conception, although some insurance companies may question prepregnancy testing (Table 1). Checking rubella, toxoplasmosis, and varicella immunity is best done preconception to confirm immunity. If the woman is nonimmune, rubella and varicella immunizations may be administered. The waiting time between rubella immunization and conception has recently been shortened from 3 months to 4 weeks.¹¹ Patients who are toxoplasmosis-negative should be reminded not to handle cat urine, feces, or litter.

View this table

Table 1. Laboratory Evaluation

Administering a rapid plasma reagin test for syphilis, counseling for HIV risk, and checking HIV status should also be done prior to pregnancy. Black patients should be screened for a genetic predisposition to sickle-cell anemia. Patients of Mediterranean descent should be screened for β-thalassemia and patients of Southeast Asian and Chinese descent should be screened for α-thalassemia. Initial screening can be performed through a complete blood cell count; a mean corpuscular volume (MCV) of more than 80 fl makes heterozygosity for α- or β-thalassemia very unlikely.¹² If the MCV is less than 80 fl, confirmatory testing for hemoglobinopathy is indicated.

In 2001, the American College of Obstetricians and Gynecologists (ACOG) recommended offering cystic fibrosis (CF) carrier screening to individuals with a positive family history, to reproductive partners of persons with CF, and to couples in whom one or both partners are white and who are planning pregnancy or seeking prenatal care.^13,14 Screening is also advised for other racial/ethnic groups who are at lower risk and in whom the test may be less sensitive.¹³ In addition, ACOG endorsed the 25-junction CF transmembrane conductance regulator gene test panel previously recommended by the American College of Medical Genetics.¹³ Practitioners are urged to obtain written informed consent to request or decline such screening.¹³

Screening programs to test Ashkenazi Jews for Tay-Sachs disease began in the 1970s. Based on their success in decreasing the number of new cases of Tay-Sachs disease, ACOG has recommended carrier testing for all couples where one or both members are of Jewish descent.¹⁵ Currently, it is recommended that all individuals of Ashkenazi Jewish, Pennsylvania Dutch, southern Louisiana Cajun, or eastern Quebec French-Canadian descent be offered testing for Tay-Sachs carrier status.¹⁵ Ideally, testing should be done prior to conception, but early-pregnancy testing can be performed with expedited results.

In the Ashkenazi Jewish population, DNA testing identifies 99.9% of Tay-Sachs carriers. For non-Jewish high-risk individuals who seek carrier testing, it is recommended to first perform a serum enzyme assay, and to confirm positive or indeterminate results by subsequent DNA mutation analysis. In a nonpregnant couple where only one individual belongs to a high-risk group, only the at-risk partner should be tested initially. If the couple is pregnant, then both individuals should be tested at the same time using both enzyme and DNA assays. As pregnancy can alter serum levels of β-hexosaminidase A (the isoenzyme whose deficiency is responsible for Tay-Sachs disease), a leukocyte assay is preferable for the mother.

Other diseases that are more common in the Ashkenazi Jewish population for which couples should consider testing include CF, Canavan disease, Gaucher disease, familial dysautonomia, Niemann-Pick disease, Fanconi anemia, Bloom syndrome, and mucolipidosis IV. Testing should optimally be done prior to pregnancy. If both partners are of Ashkenazi Jewish descent, they should both be offered screening. If only one partner is of Ashkenazi Jewish descent, then sequential screening may be performed. Both partners should be counseled on the risks of these conditions, as they are all autosomal-recessive.¹⁶

There is presently no consensus on screening for fragile X syndrome in the general population. Fragile X testing may be part of a work-up for maternal multiple pregnancy loss, but is not considered part of routine screening.¹⁷ Chromosomal studies for fragile X syndrome may also play a role in the inability of some women to become pregnant, as affected women commonly have premature ovarian failure.¹⁸

back to top

COUNSELING

Preconception counseling often covers both health and fertility issues (Table 2). Patients are generally reassured if they understand normal pregnancy rates. Many patients assume that they will become pregnant within a month or two of stopping contraception, and so need to be informed that the general pregnancy rate is 80% within 1 year.¹⁹ This can alleviate much of the anxiety that can occur when a woman has not become pregnant within the first 3 months.

View this table

Table 2. Counseling

A discussion about the likelihood of Down syndrome is important for women who will give birth after 35 years of age. Currently, it is recommended that women who are aged 35 years or older at the time of delivery should be offered prenatal genetic screening for Down syndrome via amniocentesis or chorionic villus sampling (CVS). Amniocentesis is generally performed at 15 to 16 weeks' gestation,⁴ whereas CVS is usually performed at 9 to 12 weeks.⁴ This allows for the possibility of early termination of pregnancy if desired by the couple.

Neural tube defects (NTD) are among the most common congenital malformations in the United States, at 1.2 for every 1,000 births.⁴ Folic acid supplementation can help to reduce the incidence of NTD. It is recommended that women begin taking 400 mcg/d of folic acid at least 1 month before conception and continue through the first 3 months of pregnancy.²⁰ This campaign has decreased the NTD rate in the United States.²¹ Women belonging to high-risk groups should take higher doses, and those who have seizure disorders should take at least 1 mg/d. Those who have previously given birth to a child with NTD should take at least 4 mg/d.^20,22 Other dietary recommendations include restricting high-fat foods to optimize maternal weight, limiting consumption of large fish (eg, swordfish) to no more than twice a month to reduce the risk of mercury exposure,⁸ and avoidance of foods associated with Listeria transmission (eg, sliced delicatessen meats and cheeses).²³

Other issues may include avoidance of hot tubs, as there is an increased rate of spontaneous miscarriage and fetal anomalies in women who use hot tubs in the first trimester of pregnancy.²⁴ Exercise should be encouraged, and patients can be reassured that they can continue their normal exercise regimen. If the woman has not been exercising, it is a convenient time to recommend that she begin. Women can also be reassured about the safety of sexual intercourse in early pregnancy, unless there is a problem with bleeding.

back to top

CONCLUSION

The extent of the preconception examination may preclude a brief office visit. The physician can often glean an adequate history from an intake form completed before the appointment. Another efficient method of obtaining this information is to use a standardized antenatal health history record such as the ACOG form (http://sales.acog.com/acb/stores/1/product1.cfm?SID=1&Product_ID=320), the Hollister form, or the MOM care form from the American Academy of Family Physicians (http://www.aafp.org/fpr/970300fr/15.html). The latter is especially valuable, as the questionnaire is self-administered. The physical examination portion of these forms helps the physician to include all relevant information, and lists all laboratory tests.

back to top

Cathryn Heath, MD, is clinical associate professor of family medicine, and director of maternity care; and Rhina Acevedo, MD, is clinical assistant professor and director of the Trinity Health Center in Perth Amboy, NJ. Both are in the Department of Family Medicine, University of Medicine and Dentistry of New Jersey - Robert Wood Johnson Medical School, New Brunswick.

References

1. Henshaw SK. Unintended pregnancy in the United States. Fam Plann Perspect. 1998;30(1):24-29,46.
2. Weismiller DG. Preterm labor. Am Fam Physician. 1999; 59(3):593-602.
3. Benn PA, Egan JF. Fang M, Smith-Bindman R. Changes in the utilization of prenatal diagnosis. Obstet Gynecol. 2004; 103(6):1255-1260.
4. Graves JC, Miller KE, Sellers AD. Maternal serum triple analyte screening in pregnancy. Am Fam Physician. 2002;65(5): 915-920.
5. Sadler L, Saftlas A, Wang W, Exeter M, Whittaker J, McCowan L. Treatment for cervical intraepithelial neoplasia and risk of preterm delivery JAMA. 2004;291(17):2100-2106.
6. Lumley J, Oliver S, Waters E. Interventions for promoting smoking cessation during pregnancy. Cochrane Database Syst Rev. 2000;(2):CD001055.
7. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Lead (Update). Draft for Public Comment. Atlanta, Ga: Public Health Service, US Department of Health and Human Services; 1997.
8. US Department of Health and Human Services and US Environmental Protection Agency. What you Need to Know About Mercury in Fish and Shellfish. 2004 EPA and FDA Advice for Women Who Might Become Pregnant, Women Who are Pregnant, Nursing Mothers, Young Children. EPA 823-R-04-005, 2004. Available at: http://www.cfsan.fda.gov/~dms/admehg3.html. Accessed September 8, 2004.JAMA. 1998;280(16):1405-1409.
9. Martin SL, Mackie L, Kupper LL, Buescher PA, Moracco KE. Physical abuse of women before, during, and after pregnancy. JAMA. 2001:285(12):1581-1584.
10. Petrek JA, Dukoff R, Rogatko A. Prognosis of pregnancy-associated breast cancer. Cancer. 1991;67(4):869-872.
11. American College of Obstetricians and Gynecologists. Rubella Vaccination Recommendation Changes for Pregnant Women. ACOG news release. Washington, DC: American College of Obstetricians and Gynecologists; November 29, 2002.
12. Gabbe SG. Niebyl JR, Simpson JL, Senkarik M. Obstetrics: Normal & Problem Pregnancies, 3rd ed. Philadelphia, Pa: Elsevier Health Sciences; 1996: 221-232.
13. Grody WW, Cutting GR, Klinger KW, et al. Laboratory standards and guidelines for population-based cystic fibrosis carrier screening. Genet Med. 2001;3(2):149-154.
14. American College of Obstetricians and Gynecologists, American College of Medical Genetics. Preconception and Prenatal Carrier Screening for Cystic Fibrosis: Clinical and Laboratory Guidelines. Washington, DC: American College of Obstetricians and Gynecologists; 2001.
15. Sutton VR. Tay-Sachs disease screening and counseling families at risk for metabolic disease. Obstet Gynecol Clin North Am. 2002;29(2):287-296.
16. American College of Medical Genetics. Position Statement on Carrier Testing for Canavan Disease. Bethesda, Md: American College of Medical Genetics; January 10, 1998.
17. Kornman L, Chambers H, Nisbet D, Liebelt J. Pre-conception and antenatal screening for the fragile site on the X-chromosome. Cochrane Database Syst Rev. 2002;(1):CD001806.
18. Hundscheid RD, Smits AP, Thomas CM, Kiemeney LA, Braat DD. Female carriers of fragile X premutations have no increased risk for additional diseases other than premature ovarian failure. Am J Med Genet. 2003;117A(1):6-9.
19. Hatcher RA. Contraceptive Technology, 17th ed. New York, NY: Ardent Media; 1998: 653.
20. Katz, V. Prenatal care. In: Danforth DN, Gibbs RS, Karlan BY, Haney AF, eds. Danforth's Obstetrics and Gynecology, 9th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2003.
21. Evans MI, Llurba E, Landsberger EJ, OBrien JE, Harrison HH. Impact of folic acid fortification in the United States: markedly diminished high maternal serum alpha-fetoprotein values. Obstet Gynecol. 2004;103(3):474-479.
22. Brundage SC. Preconception health care. Am Fam Physician. 2002;65(12):2507-2514.
23. FDA/Center for Food Safety and Applied Nutrition/ USDA/Food Safety and Inspection Service/Centers for Disease Control and Prevention. Quantitative Assessment of Relative Risk to Public Health from Foodborne Listeria Monocytogenes Among Selected Categories of Ready-to-Eat Foods. Available at: http://www.cfsan.fda.gov/~dms/lmr2-toc.html. Accessed September 8, 2004.
24. Li DK, Janevic T, Odouli R, Liu L. Hot tub use during pregnancy and the risk of miscarriage. Am J Epidemiol. 2003; 158(10):931-937.

back to top