For a woman with a history of type 1 diabetes and unmanageable hypertension, which change is the best choice before she plans to conceive?

The best choice for a woman with a history of type 1 diabetes and unmanageable hypertension planning to conceive is to discontinue ramipril and replace it with labetalol.

Ramipril, an ACE inhibitor, is contraindicated during pregnancy due to the risk of teratogenic effects, particularly during the second and third trimesters. Using an ACE inhibitor can lead to serious complications for the developing fetus, including renal dysfunction, oligohydramnios, and fetal death. Therefore, it's crucial for her to stop taking ramipril before conception.

Labetalol is a safe and effective antihypertensive medication that is often used to manage high blood pressure during pregnancy, making it a preferable choice. It works as a selective alpha-1 and non-selective beta-adrenergic antagonist, providing a balance of efficacy for hypertension while being considered safe for the developing fetus.

Implementing this change in antihypertensive therapy is an important step to protect both maternal health and fetal development as the woman prepares for pregnancy. The other options do not provide the necessary safety adjustment in her medication regimen, which is critical given her diabetic and hypertensive status.