“If you are having a rough day or week — it’s ok — I am, too!!!” said Serena Williams. (Ezra Shaw/Getty Images)

Since giving birth to a daughter in September, Serena Williams has been notably willing to share not only the highs of motherhood, but many of the lows she has experienced, as well. In the wake of the most lopsided loss of her career and a withdrawal from a tournament this week for previously unspecified personal reasons, Williams said on Instagram Monday that she has been in a “funk,” largely as a result of feeling that she was “not a good mom.”

The former world No. 1, who turns 37 next month, wrote that after reading that “postpartum emotions can last up to 3 years if not dealt with,” she leaned on her affinity for communication,” adding, “Talking things through with my mom, my sisters, my friends let me know that my feelings are totally normal.”

“It’s totally normal to feel like I’m not doing enough for my baby. We have all been there,” Williams said. “I work a lot, I train, and I’m trying to be the best athlete I can be.

“However, that means although I have been with her every day of her life, I’m not around as much as I would like to be. Most of you moms deal with the same thing.

“Whether stay-at-home or working, finding that balance with kids is a true art. You are the true heroes.”

For Williams, the events of the past week, which she said was “not easy,” included a 6-1, 6-0 defeat to Britain’s Johanna Konta in the first round of a tournament in San Jose. That represented the worst loss, by score, for Williams in her 23-year professional career, and it was followed by a withdrawal from this week’s Rogers Cup in Montreal.

“This is nothing but speculation on my part, but I think it can’t be easy to continue on the circuit every day with a young child,” Rogers Cup tournament director Eugene Lapierre said Saturday (via sportsnet.ca).

On the other hand, Williams has also won 23 Grand Slam singles titles in her career, one short of Margaret Court’s record for men or women, and she gave notice that more triumphs could be in her future by reaching the Wimbledon final last month. However, she has generally struggled to return to form following a 14-month layoff after a very difficult childbirth.

Williams’s fans learned how alarming the experience of giving birth to her daughter, Alexis Olympia Ohanian, was when she shared details in January. In an interview with Vogue, Williams said she underwent an emergency C-section when her heart rate dropped during contractions, and she was diagnosed with a pulmonary embolism, an illness that had previously sidelined her in 2011. This time, coughing fits from the embolism led to bleeding from her surgical incision, and after doctors addressed a large hematoma in her abdomen, she was bedridden for the first six weeks of motherhood.

That was the worst of it, from a physical standpoint, but Williams has divulged several other emotional low points, including during Wimbledon, when she tweeted that she missed her baby’s first steps. “I was training and missed it. I cried,” she said.

Last week, Williams tweeted, “Today was particularly difficult having to leave [Olympia] today to go to work. I guess some days are harder than others. Yea?”

Of course, little Olympia has also been a delight for Williams, who has frequently let her followers know when she has found immeasurable love and even inspiration in her daughter. “Not sure what I did to deserve her,” she said in May.

For Williams, though, it’s not always about what she alone is going through as a mother, but often how she can help others with their experiences of parenthood. Posting a photo of herself competing in a catsuit at the French Open in May, she tweeted, “For all the moms out there who had a tough recovery from pregnancy — here you go. If I can do it, so can you.”

That spirit of encouragement was echoed in Monday’s post, in which Williams, after acknowledging her feelings of parental inadequacy, said, “If you are having a rough day or week — it’s ok — I am, too!!!”

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