Factors That Influence Pregnancy Outcomes in Women with Lupus
- Maternal and fetal outcomes in pregnant patients with active lupus nephritis
Lupus, Volume 18, Number 4, April 2009, pp. 342 – 347
What is the topic?
Although women with lupus used to be advised to avoid getting pregnant, out of fear of complications for the mother, the baby, or both, a better understanding of the complications of lupus and improved management of lupus pregnancies have resulted in improved outcomes; today at least 85 percent of lupus pregnancies result in live births. However, doctors still advise women who have active lupus kidney disease (lupus nephritis, or LN) not to get pregnant until their disease has been inactive for at least six months.
What did the researchers hope to learn?
The researchers wanted to look at the specific impact of active LN on pregnancy outcomes (i.e., health of mother and/or baby).
Who was studied?
Fifty-eight women who became pregnant after they were diagnosed with lupus were studied. All of the women were patients at the Mayo Clinic in Rochester, Minnesota, between the years 1976 and 2007.
The women had a total of 90 pregnancies that were studied. Pregnancies that began before or right at the time of their lupus diagnosis, or which the women chose to terminate by abortion, were not included in the study. Twenty-two women in the study had more than one pregnancy.
How was the study conducted?
The researchers divided the 58 patients into three groups, depending on whether the women had active LN (16 women, 23 pregnancies), inactive (quiescent) LN (11 women, 20 pregnancies), or lupus with no history of kidney involvement (34 women, 47 pregnancies). Some of the women were listed in more than one group if they had more than one pregnancy and their LN status was different for the pregnancies. Average age at the time of the pregnancies was 28.3 years for the women with active LN, 28.2 years for those whose LN was inactive, and 25.2 years for those with no history of kidney involvement.
The researchers compared the outcomes of the pregnancies for the three different groups, looking back at the records that had been collected during the course of their treatment for lupus and their pregnancies. The records included blood tests, urine tests, antibody levels, records of disease activity, flares, and medications the patients took, as well as any complications that occurred during each pregnancy. Key measurements for pregnancy outcomes were: whether the pregnancy resulted in a live birth or fetal loss (stillbirth, or an abortion that happened spontaneously, or was performed due to the mother’s illness); the number of weeks the pregnancy lasted; and whether the baby was born at full-term (37 weeks or longer) or prematurely (less than 37 weeks). The mothers’ health measures included high blood pressure, preeclampsia, stroke, HELLP syndrome (a severe illness that can occur at the end of pregnancy), and death.
What did the researchers find?
The researchers found that women who had active LN when they became pregnant had poorer outcomes for their pregnancies than women who had lupus but no kidney disease. In contrast, the researchers found no significant differences in outcomes between pregnancies of women whose previous kidney disease was better and those with no history of kidney involvement.
Pregnancies for the women with active LN resulted in two live full-term births (9%), 12 live premature births (52%), and eight cases of fetal loss (35%), seven of which occurred prior to the 28th week of pregnancy. The average length of the pregnancies was 34 weeks.
Pregnancies for the women whose previous kidney disease was inactive resulted in nine live full-term births (45%), six live premature births (30%), and five cases of fetal loss (25%), four of which occurred before the completion of the 28th week. The average length of the pregnancies in this group was 36.5 weeks.
Pregnancies for the women with no history of kidney involvement resulted in 30 live full-term births (64%), nine live premature births (19%), and four cases of fetal loss (9%), three of which were prior to the 28th week. The average length of the pregnancies in this group was 40 weeks.
Women with active LN experienced higher rates of complications during pregnancy, with 13 (57%) developing complications, 10 of which were described as severe. Seven (35%) of the women with inactive LN had complications (four described as severe), and five (11%) of the women with no history of kidney involvement had complications. In addition, two of the women whose disease was inactive (10%) developed flares during pregnancy. One was treated with azathioprine (Imuran) with improvement, and her lupus remained inactive throughout the rest of her pregnancy. However, she delivered a stillborn baby in the 36th week. The second patient had a serious flare in her first trimester, and died several weeks later.
There was no difference in the medications used to treat the women with active or inactive kidney disease. They were more often treated with medications during their pregnancy—17 of 20 women with inactive LN (85%); 22 of 23 with active LN (96%)—than the women without kidney involvement (19 of 47, 40%). The medications prescribed were prednisone, antimalarials (such as Plaquenil®), and azathioprine (Imuran®); no women in any of the groups was treated with cyclophosphamide (Cytoxan®).
As a result of their findings, the researchers suggested that women with active LN should wait at least six months (and possibly up to 18 months) after their kidney disease has been treated and has remained inactive before becoming pregnant. Women with inactive LN seem to have about the same risks during pregnancy as women who have lupus but no history of kidney involvement.
What were the limitations of the study?
Because this study looked at the records of women over more than 31 years, the researchers could not factor in the influence of new treatments that are now being used for LN—most importantly, the growing popularity of mycophenolate mofetil (MMF) which is being given to patients both with and without active LN. (Note: MMF should not be taken during pregnancy.)
The researchers also had a relatively small number of pregnancies to study with each type of complication; when there are not a large number of cases, one or two changes in outcomes can make a big difference in terms of percentages. Furthermore, there are different types of kidney involvement in lupus, so the relatively small number of patients did not allow the researchers to look more closely at whether these different kinds of kidney disease might have affected outcomes.
There also was the possibility of bias arising from women having more than one pregnancy, since women with successful outcomes (few complications, healthy full-term babies) might be more inclined to have a second pregnancy. The researchers did recognize this potential problem and tried to account for this bias through a statistical approach.
Finally, this was a retrospective study, which means the researchers had to look back at records that were gathered for purposes other than research. In general, this kind of study is more likely to be missing information than a study that starts out in advance to follow outcomes and collect the information in a methodical way. The researchers noted this, but pointed out that the detailed record-keeping system in place at the Mayo Clinic for the 31 years provided a very strong foundation to ensure a reasonably complete collection of the results.
What do the results mean for you?
This study supports previous reports that suggest many women with lupus can have successful pregnancies, even women with a past history of kidney involvement and disease flares. Careful timing of when to get pregnant and good management of lupus disease activity can go a long way to providing the optimum outcome of fewer health complications for the mother and greater likelihood of a healthy baby.