Restrictive lung disease
Most interstitial lung diseases (ILD) occur in woman older than a child-bearing age (eg. pulmonary fibrosis), but some conditions may affect younger woman (eg. SLE, lymphangioleiomyomatosis). The reduced diffusion capacity may impair maternal oxygenation, making it difficult to meet the increased oxygen demands of late pregnancy. Pulmonary hypertension, which may complicate intersitial lung disease, increases the risk of pregnancy due to the inability of the right ventricle to meet demands for increased cardiac output. Women with ILD require close monitoring and may need supplemental oxygen therapy. Some drug therapy used for ILD may be acceptable during pregnancy (e.g. prednisone, azathioprine) but other drugs (e.g. cyclophosphamide, rituximab, mycophenolate mofetil) are usually avoided.
Abnormalitiesof the chest wall and muscles may reduce lung volumes, producing restrictive lung disease (eg. severe kyphoscoliosis, muscular dystrophy). As these women usually have normal underlying lungs, oxygenation is less of a concern. However, as pregnancy progresses the enlarging uterus may further reduce lung volumes and these women may not tolerate the increased ventilatory requirement of pregnancy, resulting in respiratory failure. Nevertheless, pregnancy is usually well tolerated despite significant pulmonary impairment. Labour and delivery may be complicated by difficult achieving epidural anesthesia due to spinal deformity, pelvic deformities affecting delivery, and the potential need for assisted delivery due to reduced pulmonary reserve.
References:
Freymond N, Cottin V, Cordier JF. Infiltrative lung diseases in pregnancy. Clin Chest Med. 32(1):133-46, 2011
Boggess KA, Easterling TR, Raghu G: Management and outcome of pregnant women with interstitial and restrictive lung disease. Am J Obstet Gynecol 173:1007–1014, 1995.
Lapinsky SE, Tram C, Mehta S, Maxwell CV. Restrictive lung disease in pregnancy. Chest 2014 (in press)