Will My Milk Supply Be the Same with My Second Baby?

While breastfeeding their first baby, many new moms wonder if their supply will be similar for any future babies. If you have low supply with your first baby, will you always have low supply? Here’s what you need to know about milk supply with your second baby.

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If my supply is low with this baby, does that mean that it also will be low with any future babies?

So the answer is: it depends.

It depends on the reason behind undersupply, and how likely this issue is likely to reoccur.

Let’s go through some potential causes of low milk supply, and the likelihood that they will happen again.

Milk removal early in lactation

One of the most important factors in establishing, maintaining, and increasing milk supply is the consistent removal of milk from the breast. (This can be via nursing, pumping, hand expression – it doesn’t matter.)

There is a theory that this is especially important early on.

The theory – it’s called prolactin receptor theory – is that removing milk frequently early on increases the number of prolactin receptor sites.

Let’s take a step back.

Prolactin is the hormone that must be present for milk to be produced. When your milk ducts are full, their walls change shape so that prolactin cannot enter via prolactin receptor sites.

This is so that a breast that’s already full slows down on milk production.

More receptor sites from more frequent milk removals early on means that – throughout your entire lactation experience – more prolactin can pass into the milk ducts and thus your milk production capability would be increased.

This means that if breastfeeding gets off to a bad start – maybe you were nursing, and baby was struggling to transfer milk and not removing much – you might not have as many prolactin receptor sites as you otherwise would have. This can make building supply still possible, but more challenging than it otherwise might have been.

The good news is that, with any future babies, sufficient milk removal is largely within your control.

Even if you plan to nurse and it doesn’t go well, you will already know how to pump, how often you need to pump, and how long you should pump for. This is knowledge that you might not have had the first time around and can help the second time.

Maternal physical causes

There are a few things on the maternal physical side that can affect milk supply.

One example is previous breast surgery (such as a breast reduction or augmentation). Whether this will affect milk supply depends on the technique used and the individual case.

Another is insufficient glandular tissue (also called IGT). This occurs when the tissue in the breast that produces milk does not develop as expected. This is caused by a variety of factors and can occur at different points in your life – in utero, in the course of puberty, or during your pregnancy.

Some signs of IGT include:

• a lack of changes in your breasts while you were pregnant,
• a wide space between your breasts on your chest, and/or
• tubular shaped breasts.

If you suspect you may have IGT, or you have had previous breast surgery, you may want to see an IBCLC to see if they are able to confirm the issue and/or offer any strategies to help.

These maternal physical causes are more likely to reoccur with each baby, though this is by no means certain and again, depends on the individual case.

Maternal hormonal concerns

There are a few hormonal issues that you might be dealing with that could affect your milk supply. Some examples include:

• Hypothyroidism
• Hyperthyroidism
• Polycystic ovarian syndrome (PCOS)
• Sheehan’s syndrome

If one of these things has affected your milk supply with this baby, it’s definitely something to watch out for but not necessarily a given that it will cause issues in the future. For example, if you are struggling with hypothyroidism now, maybe your endocrinologist will be able to work with you to find a different medication or different dosage that works better for you.

(And maybe not – obviously, this isn’t fully within your control. But it’s very possible that things could be different from baby to baby if this is your issue.)

Return of menstruation or a new pregnancy

Some people see a decline in their milk supply when they get their period back. This isn’t true for everyone, and a lot of people only see a temporary decline while they actually have their period.

For other people, though, it can be the start of a more gradual decline. For me, for example, I would lose about 5 oz when my period started, and then I’d get about 3 of those oz back when it was over. Every month when I got my period, I’d lose 2 oz for good.

A new pregnancy usually also results in a loss of milk supply due to the increased amounts of estrogen and progesterone that your body produces.

If either your period or a new pregnancy has impacted your supply, this obviously may or may not happen next time as well.

What can you do to give yourself the best chance for higher milk supply with your second baby?

So what should you take away from all of these possible causes?

I would assess which of these, if any, you think may have impacted your supply this time around. Or maybe there are other things that you can think of – like you took a medication that impacted your supply, or you got sick and your supply dropped afterwards.

Write down what you think might have been an issue this time, and then think about what you can do to mitigate that the next time around.

Again, not everything will be in your control, but there may be steps that you can take to reduce the impact of any of these issues and maximize your milk supply.

Are there any studies about milk supply and the second baby?

In addition to assessing whether or not the cause of your low milk supply is likely to reoccur, I wanted to bring up a study that we can look at to give us an idea about milk supply for subsequent babies.

This study looked at 22 mothers and measured their milk output at 1 and 4 weeks postpartum with their first and second children. They found:

Significantly more breast milk was produced at 1 week for the second lactation (an increase of 31%) and the net increase was greatest for those with the lowest milk output on the first occasion (90%). They spent less time feeding their second baby (a decrease of 20%). This increased efficiency of milk transfer was also evident at 4 weeks.

This means that even if you’re not sure what caused supply problems with this baby, there’s a good chance that things may be better with your second baby!

Finally, here’s an unscientific poll I did on Instagram about this:

Most people had the same or about the same milk supply with subsequent babies.

Have you breastfeeding more than one baby? Tell us your experience with milk supply and your second baby in the comments!

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