I came across this sentence in an online article.

Some medical literature has found that exclusively breastfeeding during the first four to six months of life may decrease your baby’s risk of developing eczema, asthma and cow’s milk allergy.

I am not quite sure why the adverb exclusively is used here to modify the gerund breastfeeding in preference to exclusive. The adverb, of course, works, but my question is would the adjective work just the same?

  • 1
    This is not an answer because I can give no authority for it. I would never use exclusive in this sentence, but exclusively does not seem quite right either because the contrary idea of promiscuously breast feeding strikes me as very weird. Nor do I think that breast feeding is even what is meant. I think what is meant is that some medical studies have found that a diet consisting exclusively of human milk during ... may prevent .... Obviously exclusively is correct there whereas exclusive is not. Nor is the method by which the milk is delivered relevant. Bad prose. Jun 24, 2018 at 1:52
  • @JeffMorrow Just so I understand you, are you saying an adjective shouldn't modify a gerund?
    – Eddie Kal
    Jun 24, 2018 at 2:00
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    Not at all. I can think of many examples where adjectives modify gerunds, e.g. quick thinking. I did not give a formal answer just because I could not articulate any grammatical rule that makes exclusive breastfeeding wrong. It sounds, however, unidiomatic to me. My best guess is that it sounds unidiomatic because the intended meaning does not concern the act of breast feeding at all, but concerns a diet consisting exclusively of human milk. The mind figures out what is meant and inserts what is required, namely an adverb modifying the participle consisting. I may well be wrong. Jun 24, 2018 at 2:18

2 Answers 2


The way I interpret the phrase is that a baby's health is improved if its only source of nutrients comes from breast milk during its first four to six months.

In that interpretation, exclusively makes sense. (In other words, it is breastfed and only breastfed.)

But the sentence has some issues with its grammar—regardless of which word is used.

It would make a lot more sense if it read:

exclusively breastfeeding your baby during its first four to six months . . .

Switching from exclusively to exclusive would also work with another tweak to the sentence:

the exclusive breastfeeding of your baby during its first four to six months . . .

(Without the mention of the baby immediately after breastfeeding, it could be interpreted as talking about the mother's act of breastfeeding alone—without regard to any particular baby.)


The practical meaning here is "breastfeeding only" as distinct from breastfeeding supplemented with "baby formula" containing soy, whey, lactose, and various oils.

The phrase you propose, exclusive breastfeeding, sounds a little comical, like the breast is a night-club for glitterati. A baby "needs to know somebody" to latch on.

A simpler phrase than exclusively breastfeeding might have been

... has shown that giving the baby only breast-milk during the first four to six months...

but that would be perceived as "non-scientific" language and not pass muster as too informal.

P.S. only must precede breast-milk so as not to be misunderstood as a restriction that goes with (only) during the first four to six months.

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