Efficacy of PRECoNCEPTIoN Care At ReduCing Pregnancy Complications Why Do I Need Preconception Care

PCC reduces the risk of congenital malformations and perinatal mortality. In 1949, Dr. Priscilla White published a landmark case series on 439 pregnancies in patients with preexisting diabetes, which highlighted the association of congenital malformations, preeclampsia and prematurity with excess perinatal mortality in infants of mothers with diabetes (11). Since that time, numerous studies have demonstrated an association between glycemic control and the occurrence of congenital malformations (12-16). Further studies have shown that PCC programs that optimize glycemic control can substantially reduce the risk of congenital malformations (17-23).

The cornerstone of PCC is the concept that hyperglycemia during organogenesis causes congenital malformations and that by avoiding hyperglycemia, congenital malformations can be prevented. Therefore, the goal of glycemic management in PCC is for the patient to attain as close to euglycemia, defined as a normal hemoglobin A1c (HbA1c), as possible while avoiding hypoglycemia (24).

One recent study demonstrating the relationship between glycemic control and outcomes was a population-based study in the Netherlands, which investigated 573 pregnancies in 301 women with preexisting diabetes between 1985 and 2003 (15). First trimester HbA1c values were identified in 474 (83%) of pregnancies. Those pregnancies in which a first trimester HbA1c was not identified were more likely to end with an adverse outcome [RR 3.3 (95% CI 2.6-4.1)]. Mean first trimester HbA1c was 7.4% (95% CI 7.3-7.5) in pregnancies terminating in good outcome as opposed to 8.5% (95% CI 8.2-8.9) in those with an adverse outcome. The investigators found a consistently positive and almost continually linear relationship between adverse outcome and first trimester HbA1c values >7%. Importantly, there was no lower threshold of HbA1c, with respect to the increased risk of malformation.

Table 1

The Three Cs of Preconception Care (PCC)

Contraception

Counseling

Care

A meta-analysis of seven older previously published studies found that for each 0.7% increase in the HbAlc, the associated risk of a congenital anomaly increased by an odds ratio of 1.2 (95% CI 1.1-1.4) (14) (see Fig. 1).

Despite the ominous relationship between hyperglycemia and pregnancy outcomes, it is clear that much of the excess risk can be avoided by attaining optimal glycemic control prior to pregnancy utilizing appropriate PCC. Kitzmiller's influential 1991 JAMA article demonstrated a greatly reduced rate of major congenital anomalies with PCC (22). In his study, 10.9% of pregnancies presenting after conception were complicated by congenital anomalies compared with only 1.2% of pregnancies that had received PCC. The success was attributed largely to early glycemic control.

The Maine Diabetes in Pregnancy Project went a step further to demonstrate a reduction in perinatal mortality through PCC (23). This study included women with preexisting diabetes and focused on good diabetes control before conception, the benefits of preconception counseling and appropriate antepartum and postpartum care. The effort resulted in significant improvements in fetal and neonatal death rates in offspring of women with DM1 and DM2, even though the women who received PCC were older and had diabetes for a longer period of time.

The Diabetes Control and Complications Trial (DCCT) had less dramatic but still consistent results (21 ). It reviewed 270 pregnancies in 180 women with DM1 from 1983 to 1993. The women had been placed in one of two groups - an intensive therapy group or a conventional therapy group. At conception, the intensive therapy group had significantly lower HbA1c than the conventional therapy group (7.4 ± 1.3% vs. 8.1 ± 1.7%, respectively), and there was a trend toward reduced congenital malformations (P = 0.06). The intensive insulin group had a very low 1% incidence of congenital anomalies, comparable to the rates noted for the general population. Another evaluation of pregnancies in women with DM1 found that only women with a normal early pregnancy HbA1c (<5.6%) had a rate of congenital malformation comparable to the general population (20).

Hemoglobin A1c Congenital Malformations
Fig. 1. Preconception hemoglobin A1c vs. absolute risk of congenital anomaly (solid) and 95% CI (14). (Copyright © 2007 American Diabetes Association. From Diabetes Care®, Vol. 30, 2007; 1920-1925. Reprinted with permission from The American Diabetes Association.).

Another study analyzed the efficacy of PCC in a single center throughout time from before a program for PCC planning was in place until after funding for the center expired. They found that perinatal mortality in women with type 1 diabetes fell to zero occurrences by the end of the funding period and that congenital malformations also declined (18) (see Fig. 2).

The efficacy of PCC was analyzed in a 2001 metaanalysis, which found that patients undergoing PCC had lower early first trimester glycated hemoglobin. Pooled results indicate a marked reduction in major and minor congenital anomalies [2.4% (PCC) vs. 7.7% (no PCC)] even though PCC patients were older. When prospective studies were analyzed separately, the relative risk of congenital anomalies was 0.42 (95% CI 0.22-0.60) in those who received PCC (9).

More recently, the Scottish Diabetes in Pregnancy Study found that the lowest rates of adverse pregnancy outcomes in women with DM1 occurred in those who had attained optimal HgbAlc (<7.0%) before discontinuing contraception (25).

A 2006 prospective cohort study of women with DM1 identified that a PCC program that advocated education and attainment of preprandial blood glucose <6 mmol/l, postprandial blood glucose <8 mmol/l, and HbA1c <7.5% prior to conception led to significantly fewer adverse outcomes of pregnancy (malformations, stillbirths and neonatal deaths) (19). There was a 2.9% adverse event rate in women receiving PCC compared with a 10.2% rate in those who did not receive PCC (P = 0.03), and the occurrence of premature delivery was also significantly lower.

An interesting comparison of congenital anomaly rates among different types of diabetes found that patients with "gestational diabetes" who were found after pregnancy from testing to actually have DM2 had a similar rate of congenital malformation as those with preexisting DM2 (26).

40 i

40 i

'73-78 '7^-83 'xi-KH '80-93 "9?99 Prior PPC I PP<; II ppy III POTt

Fig. 2. Preconception enrollment, perinatal mortality, and congenital malformation rates for periods before, during, and after diabetes in Pregnancy Program Project Grant (PPG) at the University of Cincinnati from 1973 to 1999 (18). (Reprinted (with permission) from Sherrie S. McElvy. A focused preconceptional and early pregnancy program in women with type 1 diabetes reduces perinatal mortality and malformation rates to general population levels. The Journal of Maternal-Fetal Medicine 2000;9:14-20.).

'73-78 '7^-83 'xi-KH '80-93 "9?99 Prior PPC I PP<; II ppy III POTt

Fig. 2. Preconception enrollment, perinatal mortality, and congenital malformation rates for periods before, during, and after diabetes in Pregnancy Program Project Grant (PPG) at the University of Cincinnati from 1973 to 1999 (18). (Reprinted (with permission) from Sherrie S. McElvy. A focused preconceptional and early pregnancy program in women with type 1 diabetes reduces perinatal mortality and malformation rates to general population levels. The Journal of Maternal-Fetal Medicine 2000;9:14-20.).

While all PCC programs stress the importance of good glycemic control, there are additional benefits of PCC, including counseling women about the importance of taking a prenatal multivitamin, which can reduce neural tube defects as just one example (27). The efficacy of PCC programs at reducing congenital malformations and perinatal mortality is clearly well established.

Recommendation. All women with preexisting diabetes should receive PCC from a multidisciplinary team familiar with the area of diabetes and pregnancy.

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