Letters

I applaud Dr. Anita L. Nelson for prioritizing breast-feeding enough to study the effects of medications on milk supply ("Postpartum DMPA Doesn't Prevent Lactation" Jan. 1, 2002, p. 7). It is interesting that the duration of lactation was not different in the study groups, but does this prove that the contraceptive is not interfering with lactation or that it has no effect on milk supply?

Most mothers in the study reported that they didn't have enough milk, but it is not clear whether this was real or perceived. If it is real, and if injection of depot medroxyprogesterone acetate (DMPA) is not the cause of a low milk supply what is?

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It also is true that many hospital practices interfere with milk supply and that many mothers misread or misunderstand normal infant feeding cues. Many don't know that there are growths spurts in the first few weeks of life that are characterized by increased feeding frequencies. Simply because there were equal numbers of mothers reporting that there was a problem with milk supply, one cannot assume that the group given the DMPA did not have an actual lack of milk unless milk output was measured, which is unclear in the report.

The main objection to use of DMPA before 5 days postpartum is that it will intherefere with lactogenesis II (the "milk coming in"), and it would be useful to have an assessment of a delay in this event.

Finally, given all the hospital practices that can interfere with milk supply and the apparent lack of measurement of milk output, has this study really proved that DMPA doesn't lower milk supply? Or do all theother confounding factors simply have a greater combined effect than that of DMPA?

Christine Betzold

nurse-practitioner/lactation consultant

Garden Grove, Calif.

Dr. Nelson replies:

Ms. Betzold reinforces the concept that ever more research is needed to answer more sophisticated scientific questions. However, based on the reassuring information we have today about the short, intermediate, and long-term effects that DMPA has on breast-feeding, one would hope that no one caring for postpartum women would withhold access to this effective method for birth control to breast-feeding women.

Rather then asking, "Are we absolutely certain that the studies perfectly guarantee that there is no adverse impact on the quantity of breast milk produced?" we should be asking, "Where is the evidence that DMPA has any deleterious impact?"

We tried to determine if women using progestin-only methods had different rates of lactation, continuation, or supplemental feeding in the immediate postpartum period. Not only was there no overall difference in those rates, but there was no difference in the rates of discontinuation or supplementation due to the lack of milk formation. Generally, babies do let their mothers know when they are hungry. There were many other reasons why women stopped breast-feeding: return to work, preference, scheduling problems. This only underscores the need to provide them with effective contraception. We also examined the literature that raised the concern about DMPA in breast-feeding women and found the concerns to be very theoretical, based primarily on animal data.

In our group of indigent women who can ill afford another pregnancy, it was indeed important to find that breast-feeding rates were not diminished by DMPA use. In our estimation, it should not be withheld from use by breast-feeding postpartum women.

Vacuum Extraction

Dr. Dirk E. Peterson questioned why the vacuum extractor should have a maximum use of no more than 15-20 minutes ("Vacuum Extraction Issues," April 15, 2002, p. 6).

The original vacuum extractor, Malmstrom's in particular, had a metal cup with a screen and worked on a principle of generating a caput that molded into the cup of the extractor. This process took several minutes to generate the caput. The use of the Malmstrom extractor did not allow a relaxation of vacuum between patient pushes. Using this device for more than 20 minutes had a risk of causing considerable necrosis of the infant's scalp. It always caused a huge caput and the patient had to be warned that the baby would look "funny" for at least a few days.

The newer vacuum extractors are made of Silastic or some other form of plastic and the vacuum does not need to be maintained when te patient is not pushing. I don't think there is a mandatory 20-minute limit with the newer extractors, but if the head cannot be brought down to a forceps-deliverable point in three contractoins, a cesarean section is indicated. I use the term forceps-deliverable point, as these instruments complement each other and vacuum extraction alone may not get the baby out.

Robert Frischer, M.D.

Wichita Falls, Tex.

Hair Color Irrelevant

Dr. Anita Nelson said that oral contraceptives were first developed "by grayhaired guys...who decided women wanted to have a period every month" ("Doctors Urged to Offer Continuous Contraception," June 15, 2002, p. 14).

The "Gray-haired guy" remark was as insulting and unacceptable as a "blonde babe" remark would have been. Dr. Nelson should take the high ground and stop putting labels on people to suit her prejudices.