Want to keep your employees who have recently had children? An extra perk or two can go a long way. 

Companies across a variety of industries are offering working parents generous benefits like discounts on cribs and free breast milk shipping for mothers on business trips. One of the drivers of this trend is the fact that retaining female employees after they become mothers is a significant challenge for many companies, human resource experts told Inc. More than one-third of American women don't return to work after giving birth, according to a 2017 report on motherhood by the health data company Ovia.

"[Offering parental benefits] is part of a broad movement around diversity and more women staying in the workforce," says Julie Li, the senior director of people operations at the HR software company Namely. "[Companies have] realized they weren't providing the support they needed to make sure those individuals are successful."

Recently, generous maternity benefits have started popping up even at midsize businesses, not just large corporations with hefty budgets, hiring managers told Inc. Here are three benefits companies are offering new parents. 

1. Breast milk shipping

At the online real estate marketplace Zillow, nursing mothers who are traveling for work can ship their breast milk home overnight for free. The company offers this benefit through the delivery service Milk Stork, which sends a ready-to-ship cooler to the employee's hotel. Zillow Group's chief people officer, Dan Spaulding, says the perk is a selling point for prospective hires.

"These benefits are a signal we are a workplace that listens to the needs of our employees, and we think that's a differentiator in building relationships with candidates," Spaulding says. "Year-over-year, we continue to have more women apply to Zillow." He added that the average annual cost to offer this perk, which between 12 and 15 employees use every month, comes out to around $25,000.

Founded in 2015, Palo Alto, California-based Milk Stork grew its number of enterprise clients by 60 percent in 2018, to 400, according to the company. Other businesses that use the service include PayPal, Pinterest, and Trip Advisor.

2. High-tech cribs

A well-rested employee is a happier employee. To help new parents weather the first few months of caring for an infant who wakes around the clock, some companies are offering employees a steep discount on the Snoo, a tech-enabled crib that promises to soothe babies--and hopefully put them back to sleep--by imitating the sounds and motions of the womb. One such employer, the wireless tech company Qualcomm, offers its employees a 20 percent discount on the $1,295 bassinet. Qualcomm's employee engagement manager, Christi Gilhoi, says prospective hires increasingly care about benefits surrounding parenthood.

"People who are thinking about starting a family want to know how the culture supports new families," Gilhoi says. 

Launched in 2016 by Los Angeles-based Happiest Baby, the Snoo was developed by pediatrician and child development specialist Dr. Harvey Karp. Happiest Baby has a partnership with Qualcomm that allows the company to offer discounted cribs to employees at no cost. Around 30 companies have similar partnerships with Happiest Baby, including Salesforce, Snap, and WW, formally known as Weight Watchers. 

3. Paid travel for caregivers

The outdoor retailer Patagonia allows mothers who are still nursing to bring a caregiver on business trips. This can include the mother's partner, a nanny, or one of Patagonia's on-site childcare professionals.

"When women are able to be at work, be present, and not drop out of the workforce, they have been able to perform and advance with their peers at the same level," says Dean Carter, Patagonia's vice president of human resources. "We have a lot of women who are in leadership positions, and we want to help them be moms and get work done." The perk has helped 95 percent of Patagonia's employees who take maternity leave return to the company, according to Carter.

If you're thinking about readjusting your company's policies but don't have the resources to offer similar perks, Namely's Li says to focus simply on offering flexibility with both mothers and fathers who are returning to work after having a child.

"Both retention and attraction are going to benefit greatly from all these changes in policies," Li says. "It's important to build a culture where you really value employees and make sure they are well supported."