Expressing breast milk: Are some methods better than others?

Women can express milk by hand using specific hand movements to stimulate the flow of milk in their breasts. No equipment is needed, other than something to collect the milk in. You can try it yourself or ask a midwife, lactation consultant or an experienced mother to show you how to do it. Most women will need a bit of time and practice to get the hang of it.

Breast pumps create suction pressure on the outside of the nipple, which pulls or “sucks” milk out of the breast. The simplest types of breast pumps are manual pumps that generate suction with a piston, lever or hollow rubber ball. A bit of practice is often needed to get the hang of using these too. Some manual pumps can be difficult to use. There are pumps that can be operated using just one hand, so you could theoretically use two at the same time.

Electric pumps of various sizes are also available. Some are battery-operated. It is usually possible to regulate the pump’s suction strength. Some also pump at intervals to copy the rhythmic sucking behavior of a baby.

Many electric pumps can be used on both breasts at the same time. They are quite a lot more expensive than manual pumps. In Germany, you can rent one at a fairly low cost from a midwife, pharmacy or medical supply store. If you need it for medical reasons, a doctor can give you a prescription for the rental pump.

All breast pumps can have unpleasant side effects: Some women, for example, find that their nipples become sore and irritated. Here it is helpful to try out several types of pump with different attachments. Some women find expressing milk stressful and awkward, or they may have problems operating the pump. As a result, less milk may come out or they might give up altogether. If you are having difficulties, it can be helpful to talk to an experienced friend, midwife or lactation consultant.

It is very important that you wash your hands before expressing milk, and always thoroughly disinfect, boil or steam-clean the pump and accessories to kill any germs. It is also important to cool the milk or freeze it straight away if you don’t want to give it to your baby immediately, to keep it germ-free. According to the German National Breastfeeding Commission (Nationale Stillkommission), breast milk should only be kept in the fridge for up to three days, and should only be kept in the freezer for up to six months. When refrigerating or freezing milk, it is important to label the milk container with the date the milk was expressed, so you can see how old it is.

Researchers from the Cochrane Collaboration – an international research network – wanted to find out which method of expressing breast milk is the most effective, the safest and the most comfortable. They looked for studies comparing different methods of expressing breast milk. They found 41 studies in total, but only 22 of them – involving a total of 1,340 participants – provided suitable data. These studies were carried out in several countries, including the U.S., England, Brazil, Malaysia and Nigeria. The participants were randomly assigned to groups that used different methods of expressing milk. In some of the 22 studies, the participants were mothers who had recently given birth to babies who were preterm, underweight or ill.

The research suggests that bacterial contamination is quite rare in expressed milk. None of the methods was associated with more cases of bacterial contamination either. There is also no indication that any of these methods are associated with more breast or nipple pain.

Whether the women used an electric pump on both breasts or expressed milk by hand, the studies didn't find any significant differences between the different approaches here. But they didn't offer any information about which exact technique the women used when expressing by hand, or whether they had been given good instructions – both of which can greatly influence the outcome. The difference between the amounts of milk expressed was also too small to be truly significant. The amount of milk produced varies from woman to woman anyway, and not very many women took part in the studies, so it's not clear whether the difference in the amount of milk expressed was really due to the method used. The researchers didn't find any significant differences between the amounts of milk expressed using electric pumps and manual pumps either.

One other thing the researchers were interested in was how long it takes to get a certain amount of milk using the different methods. Women who used an electric pump needed less time than women who used a manual pump. But it's worth noting that when the women in the studies used electric pumps, they usually used them on both breasts, which wasn't possible with the manual pumps that were used. As the Cochrane researchers pointed out, though, other studies have found that many women feel uncomfortable using a pump on both breasts at the same time.

Some studies looked at whether things like listening to relaxing music, massaging the breast, or using warm compresses have any influence on the amount of milk expressed. Their results suggest that these methods may make expressing milk easier and increase the amount of milk.

All of the studies were very small and only tested a few pumps, so no truly reliable conclusions can be drawn from them. Also, many of the studies were funded by the manufacturers of the pumps that were tested. More independent research is needed to be more sure about which method is the safest, the most effective and the most comfortable.